Shares are created to make part or all of a volume accessible to other computers on the network. The type of share to create depends on factors like which operating systems are being used by computers on the network, security requirements, and expectations for network transfer speeds.
FreeNAS® provides a Wizard for creating shares. The Wizard automatically creates the correct type of dataset and permissions for the type of share, sets the default permissions for the share type, and starts the service needed by the share. It is recommended to use the Wizard to create shares, fine-tune the share settings using the instructions in the rest of this chapter if needed, then fine-tune the default permissions from the client operating system to meet the requirements of the network.
Shares are created to provide and control access to an area of storage. Before creating shares, it is recommended to make a list of the users that need access to storage data, which operating systems these users are using, whether all users should have the same permissions to the stored data, and whether these users should authenticate before accessing the data. This information can help determine which type of shares are needed, whether multiple datasets are needed to divide the storage into areas with different access and permissions, and how complex it will be to set up those permission requirements. Note that shares are used to provide access to data. When a share is deleted, it removes access to data but does not delete the data itself.
These types of shares and services are available:
- AFP: Apple File Protocol shares are often used when the client computers all run Mac OS X. Apple has slowly shifted to preferring SMB for modern networks, although Time Machine still requires AFP.
- Unix (NFS): Network File System shares are accessible from Mac OS X, Linux, BSD, and the professional and enterprise versions (but not the home editions) of Windows. This can be are a good choice when the client computers do not all run the same operating system but NFS client software is available for all of them.
- WebDAV: WebDAV shares are accessible using an authenticated web browser (read-only) or WebDAV client running on any operating system.
- SMB: Server Message Block shares, also known as Common Internet File System (CIFS) shares, are accessible by Windows, Mac OS X, Linux, and BSD computers. Access is slower than an NFS share due to the single-threaded design of Samba. SMB provides more configuration options than NFS and is a good choice on a network for Windows systems. However, it is a poor choice if the CPU on the FreeNAS® system is limited; if the CPU is maxed out, upgrade the CPU or consider another type of share.
- Block (iSCSI): block or iSCSI shares appear as an unformatted disk to clients running iSCSI initiator software or a virtualization solution such as VMware. These are usually used as virtual drives.
Fast access from any operating system can be obtained by configuring the FTP service instead of a share and using a cross-platform FTP file manager application such as Filezilla. Secure FTP can be configured if the data needs to be encrypted.
When data security is a concern and the network users are familiar with SSH command line utilities or WinSCP, consider using the SSH service instead of a share. It is slower than unencrypted FTP due to the encryption overhead, but the data passing through the network is encrypted.
It is generally a mistake to share a volume or dataset with more than one share type or access method. Different types of shares and services use different file locking methods. For example, if the same volume is configured to use both NFS and FTP, NFS will lock a file for editing by an NFS user, but an FTP user can simultaneously edit or delete that file. This results in lost edits and confused users. Another example: if a volume is configured for both AFP and SMB, Windows users can be confused by the “extra” filenames used by Mac files and delete them. This corrupts the files on the AFP share. Pick the one type of share or service that makes the most sense for the types of clients accessing that volume, and use that single type of share or service. To support multiple types of shares, divide the volume into datasets and use one dataset per share.
This section demonstrates configuration and fine-tuning of AFP, NFS, SMB, WebDAV, and iSCSI shares. FTP and SSH configurations are described in Services.
10.1. Apple (AFP) Shares¶
FreeNAS® uses the Netatalk AFP server to share data with Apple systems. This section describes the configuration screen for fine-tuning AFP shares created using the Wizard. It then provides configuration examples for using the Wizard to create a guest share, configuring Time Machine to back up to a dataset on the FreeNAS® system, and for connecting to the share from a Mac OS X client.
To view the AFP share created by the Wizard, click Sharing ‣ Apple (AFP) and highlight the name of the share. Click its Edit button to see the configuration options shown in Figure 10.1.1. The values showing for these options will vary, depending upon the information given when the share was created.
Table 10.1.1 summarizes the options available to fine-tune an AFP share. These options should usually be left at the default settings. Changing them might cause unexpected behavior. Most settings are only available with Advanced Mode. Do not change an advanced option without fully understanding the function of that option. Refer to Setting up Netatalk for a more detailed explanation of these options.
|Path||browse button||browse to the volume/dataset to share; do not nest additional volumes, datasets, or symbolic links beneath this path because Netatalk does not fully support that|
|Name||string||volume name which appears in the Mac computer’s connect to server dialog; limited to 27 characters and cannot contain a period|
|Share Comment||string||✓||optional comment|
|Allow List||string||✓||comma-delimited list of allowed users and/or groups where groupname begins with a
|Deny List||string||✓||comma-delimited list of denied users and/or groups where groupname begins with a
|Read-only Access||string||✓||comma-delimited list of users and/or groups who only have read access where groupname begins with a
|Read-write Access||string||✓||comma-delimited list of users and/or groups who have read and write access where groupname begins with a
|Time Machine||checkbox||when checked, FreeNAS® advertises itself as a Time Machine disk so it can be found by Macs; due to a limitation in how the Mac deals with low-diskspace issues when multiple Macs share the same volume, checking Time Machine on multiple shares could result in intermittent failed backups|
|Time Machine Quota||checkbox||only appears when Time Machine is checked; when checked, each time machine backup on the share has its own quota|
|Zero Device Numbers||checkbox||✓||enable when the device number is not constant across a reboot|
|No Stat||checkbox||✓||if checked, AFP does not stat the volume path when enumerating the volumes list; useful for automounting or volumes created by a preexec script|
|AFP3 UNIX Privs||checkbox||✓||enable Unix privileges supported by OSX 10.5 and higher; do not enable this if the network contains Mac OS X 10.4 clients or lower as they do not support this feature|
|Default file permission||checkboxes||✓||only works with Unix ACLs; new files created on the share are set with the selected permissions|
|Default directory permission||checkboxes||✓||only works with Unix ACLs; new directories created on the share are set with the selected permissions|
|Default umask||integer||✓||umask used for newly created files, default is 000 (anyone can read, write, and execute)|
|Hosts Allow||string||✓||comma-, space-, or tab-delimited list of allowed hostnames or IP addresses|
|Hosts Deny||string||✓||comma-, space-, or tab-delimited list of denied hostnames or IP addresses|
|Auxiliary Parameters||string||additional afp.conf parameters not covered by other option fields|
10.1.1. Creating AFP Guest Shares¶
AFP supports guest logins, meaning that Mac OS X users can access the AFP share without requiring their user accounts to first be created on or imported into the FreeNAS® system.
When a guest share is created along with a share that requires authentication, AFP only maps users who log in as guest to the guest share. If a user logs in to the share that requires authentication, permissions on the guest share can prevent that user from writing to the guest share. The only way to allow both guest and authenticated users to write to a guest share is to set the permissions on the guest share to 777 or to add the authenticated users to a guest group and set the permissions to 77x.
Before creating a guest share, go to Services ‣ AFP and make sure that the Guest Access box is checked.
To create the AFP guest share, click Wizard, then click the Next button twice to display the screen shown in Figure 10.1.2. Complete these fields in this screen:
- Share name: enter a name for the share that is identifiable but less than 27 characters long. This name cannot contain a period. In this example, the share is named afp_guest.
- Click the button for Mac OS X (AFP).
- Click the Ownership button. Click the drop-down User menu and select nobody. Click the Return button to return to the previous screen.
- Click the Add button. The share is not created until the button is clicked. Clicking the Add button adds an entry to the Name frame with the name that was entered in Share name.
Click the Next button twice, then the Confirm button to create the share. The Wizard automatically creates a dataset for the share that contains the correct default permissions and starts the AFP service so the share is immediately available. The new share is also added as an entry to Sharing ‣ Apple (AFP).
Mac OS X users can connect to the guest AFP share by clicking Go ‣ Connect to Server. In the example shown in Figure 10.1.3, the user has entered afp:// followed by the IP address of the FreeNAS® system.
Click the Connect button. Once connected, Finder opens automatically. The name of the AFP share is displayed in the SHARED section in the left frame and the contents of any data saved in the share is displayed in the right frame.
To disconnect from the volume, click the eject button in the Shared sidebar.
10.1.2. Creating Authenticated and Time Machine Shares¶
Mac OS X includes the Time Machine application which can be used to schedule automatic backups. In this configuration example, a Time Machine user will be configured to backup to an AFP share on a FreeNAS® system. It is recommended to create a separate Time Machine share for each user that will be using Time Machine to backup their Mac OS X system to FreeNAS®. The process for creating an authenticated share for a user is the same as creating a Time Machine share for that user.
To use the Wizard to create an authenticated or Time Machine share, enter the following information, as seen in the example in Figure 10.1.4.
- Share name: enter a name for the share that is identifiable but less than 27 characters long. The name cannot contain a period. In this example, the share is named backup_user1.
- Click the button for Mac OS X (AFP) and check the box for Time Machine.
- Click the Ownership button. If the user already exists on the FreeNAS® system, click the drop-down User menu to select their user account. If the user does not yet exist on the FreeNAS® system, type their name into the User field and check the Create User checkbox. If the user will be a member of a group that already exists on the FreeNAS® system, click the drop-down Group menu to select the group name. To create a new group to be used by Time Machine users, enter the name in the Group field and check the Create Group checkbox. Otherwise, enter the same name as the user. In the example shown in Figure 10.1.5, both a new user1 user and a new tm_backups group will be created. Since a new user is being created, this screen prompts for the user password to be used when accessing the share. It also provides an opportunity to change the default permissions on the share. When finished, click Return to return to the screen shown in Figure 10.1.4.
- Click the Add button. Remember to do this or the share will not be created. Clicking the Add button adds an entry to the Name frame with the name that was entered in Share name.
To configure multiple authenticated or Time Machine shares, repeat for each user, giving each user their own Share name and Ownership. When finished, click the Next button twice, then the Confirm button to create the shares. The Wizard automatically creates a dataset for each share with the correct ownership and starts the AFP service so the shares are immediately available. The new shares are also added to Sharing ‣ Apple (AFP).
At this point, it may be desirable to configure a quota for each Time Machine share, to restrict backups from using all of the available space on the FreeNAS® system. The first time Time Machine makes a backup, it will create a full backup after waiting two minutes. It will then create a one hour incremental backup for the next 24 hours, and then one backup each day, each week and each month. Since the oldest backups are deleted when a Time Machine share becomes full, make sure that the quota size is sufficient to hold the desired number of backups. Note that a default installation of Mac OS X is ~21 GB in size.
To configure a quota, go to Storage ‣ Volumes and highlight the entry for the share. In the example shown in Figure 10.1.6, the Time Machine share name is backup_user1. Click the Edit Options button for the share, then Advanced Mode. Enter a value in the Quota for this dataset field, then click Edit Dataset to save the change. In this example, the Time Machine share is restricted to 200 GB.
An alternative is to create a global quota using the instructions in Set up Time Machine for multiple machines with OSX Server-Style Quotas.
To configure Time Machine on the Mac OS X client, go to System Preferences ‣ Time Machine which opens the screen shown in Figure 10.1.7. Click ON and a pop-up menu shows the FreeNAS® system as a backup option. In our example, it is listed as backup_user1 on “freenas”. Highlight the FreeNAS® system and click Use Backup Disk. A connection bar opens and prompts for the user account’s password–in this example, the password that was set for the user1 account.
If Time Machine could not complete the backup. The backup disk image could not be created (error 45) is shown when backing up to the FreeNAS® system, a sparsebundle image must be created using these instructions.
If Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you. is shown, follow the instructions in this post to avoid making another backup or losing past backups.
10.2. Unix (NFS) Shares¶
FreeNAS® supports sharing over the Network File System (NFS). Clients use the mount command to mount the share. Once mounted, the NFS share appears as just another directory on the client system. Some Linux distros require the installation of additional software in order to mount an NFS share. On Windows systems, enable Services for NFS in the Ultimate or Enterprise editions or install an NFS client application.
For performance reasons, iSCSI is preferred to NFS shares when FreeNAS® is installed on ESXi. When considering creating NFS shares on ESXi, read through the performance analysis at Running ZFS over NFS as a VMware Store.
To create an NFS share using the Wizard, click the Next button twice to display the screen shown in Figure 10.2.1. Enter a Share name. Spaces are not allowed in these names. Click the button for Generic Unix (NFS), then click Add so the share name appears in the Name frame. When finished, click the Next button twice, then the Confirm button to create the share. Creating an NFS share using the wizard automatically creates a new dataset for the share, starts the services required for NFS, and adds an entry in Sharing ‣ Unix (NFS) Shares. Depending on your requirements, the IP addresses that are allowed to access the NFS share can be restricted, or the permissions adjusted.
NFS shares are edited by clicking Sharing ‣ Unix (NFS), highlighting the entry for the share, and clicking its Edit button. In the example shown in Figure 10.2.2, the configuration screen is open for the nfs_share1 share.
Table 10.2.1 summarizes the available configuration options in this screen. Some settings are only available by clicking the Advanced Mode button.
|Path||browse button||browse to the volume or dataset to be shared; click Add extra path to select multiple paths|
|Comment||string||set the share name; if left empty, share name is the list of selected Path entries|
|Authorized networks||string||✓||list of allowed networks in network/mask CIDR notation, like 126.96.36.199/24, space-delimited; leave empty to allow all|
|Authorized IP addresses or hosts||string||✓||list of allowed IP addresses or hostnames, space-delimited; leave empty to allow all|
|All directories||checkbox||when checked, allow the client to mount any subdirectory within the Path|
|Read only||checkbox||prohibit writing to the share|
|Quiet||checkbox||✓||inhibit otherwise-useful syslog diagnostics to avoid some annoying error messages; see exports(5) for examples|
|Maproot User||drop-down menu||✓||when a user is selected, the root user is limited to that user’s permissions|
|Maproot Group||drop-down menu||✓||when a group is selected, the root user is also limited to that group’s permissions|
|Mapall User||drop-down menu||✓||the specified user’s permissions are used by all clients|
|Mapall Group||drop-down menu||✓||the specified group’s permissions are used by all clients|
|Security||selection||✓||only appears if Enable NFSv4 is checked in Services ‣ NFS; choices are sys or these Kerberos options: krb5 (authentication only), krb5i (authentication and integrity), or krb5p (authentication and privacy); if multiple security mechanisms are added to the Selected column using the arrows, use the Up or Down buttons to list in order of preference|
When creating NFS shares, keep these points in mind:
- Clients will specify the Path when mounting the share.
- The Maproot and Mapall options are exclusive, meaning only one can be used–the GUI does not allow both. The Mapall options supersede the Maproot options. To restrict only the root user’s permissions, set the Maproot option. To restrict permissions of all users, set the Mapall options.
- Each volume or dataset is considered to be its own filesystem and NFS is not able to cross filesystem boundaries.
- The network or host must be unique per share and per filesystem or directory.
- The All directories option can only be used once per share per filesystem.
To better understand these restrictions, consider a scenario where there are:
- two networks, 10.0.0.0/8 and 188.8.131.52/8
- a ZFS volume named
volume1with 2 datasets named
dataset1contains a directory named
Because of restriction #3, an error is shown when trying to create one NFS share like this:
- Authorized networks set to 10.0.0.0/8 184.108.40.206/8
- Path set to
Instead, set a Path of
check the All directories box.
That directory could also be restricted to one of the networks by creating two shares instead:
First NFS share:
- Authorized networks set to 10.0.0.0/8
- Path set to
Second NFS share:
- Authorized networks set to 220.127.116.11/8
- Path set to
Note that this requires the creation of two shares. It cannot be done with only one share.
10.2.1. Example Configuration¶
By default, the Mapall fields are not set. This means that when a user connects to the NFS share, the user has the permissions associated with their user account. This is a security risk if a user is able to connect as root as they will have complete access to the share.
A better option is to do this:
- Specify the built-in nobody account to be used for NFS access.
- In the Change Permissions screen of the volume/dataset that is being shared, change the owner and group to nobody and set the permissions according to your requirements.
- Select nobody in the Mapall User and Mapall Group drop-down menus for the share in Sharing ‣ Unix (NFS) Shares.
With this configuration, it does not matter which user account connects to the NFS share, as it will be mapped to the nobody user account and will only have the permissions that were specified on the volume/dataset. For example, even if the root user is able to connect, it will not gain root access to the share.
10.2.2. Connecting to the Share¶
The following examples share this configuration:
- The FreeNAS® system is at IP address 192.168.2.2.
- A dataset named
/mnt/volume1/nfs_share1is created and the permissions set to the nobody user account and the nobody group.
- An NFS share is created with these attributes:
- Authorized Networks: 192.168.2.0/24
- All Directories checkbox is checked
- MapAll User is set to nobody
- MapAll Group is set to nobody
10.2.2.1. From BSD or Linux¶
NFS shares are mounted on BSD or Linux clients with this command executed as the superuser (root) or with sudo:
mount -t nfs 192.168.2.2:/mnt/volume1/nfs_share1 /mnt
- -t nfs specifies the filesystem type of the share
- 192.168.2.2 is the IP address of the FreeNAS® system
- /mnt/volume/nfs_share1 is the name of the directory to be shared, a dataset in this case
- /mnt is the mountpoint on the client system. This must be an existing, empty directory. The data in the NFS share appears in this directory on the client computer.
A successful mounting of the share returns to the command prompt without any status or error messages.
If this command fails on a Linux system, make sure that the nfs-utils package is installed.
This configuration allows users on the client system to copy files to
/mnt (the mount point). All files are owned by
nobody:nobody. Changes to any files or directories in
are written to the FreeNAS® system’s
Settings cannot be changed on the NFS share if it is mounted on any client computers. The umount command is used to unmount the share on BSD and Linux clients. Run it as the superuser or with sudo on each client computer:
10.2.2.2. From Microsoft¶
Windows NFS client support varies with versions and releases. For best results, use Windows (SMB) Shares.
10.2.2.3. From Mac OS X¶
To mount the NFS volume from a Mac OS X client, click on Go ‣ Connect to Server. In the Server Address field, enter nfs:// followed by the IP address of the FreeNAS® system and the name of the volume/dataset being shared by NFS. The example shown in Figure 10.2.3 continues with our example of 192.168.2.2:/mnt/volume1/nfs_share1.
Finder opens automatically after connecting. The IP address of the
FreeNAS® system is displayed in the SHARED section in the left frame
and the contents of the share are displayed in the right frame. In the
example shown in
/mnt/data has one folder named
images. The user can
now copy files to and from the share.
10.2.3. Troubleshooting NFS¶
Some NFS clients do not support the NLM (Network Lock Manager) protocol used by NFS. This is the case if the client receives an error that all or part of the file may be locked when a file transfer is attempted. To resolve this error, add the option -o nolock when running the mount command on the client to allow write access to the NFS share.
If a “time out giving up” error is shown when trying to mount the share from a Linux system, make sure that the portmapper service is running on the Linux client. If portmapper is running and timeouts are still shown, force the use of TCP by including -o tcp in the mount command.
If a “RPC: Program not registered” error is shown, upgrade to the latest version of FreeNAS® and restart the NFS service after the upgrade to clear the NFS cache.
If clients see “reverse DNS” errors, add the FreeNAS® IP address in the Host name database field of Network ‣ Global Configuration.
If clients receive timeout errors when trying to mount the share, add the client IP address and hostname to the Host name data base field in Network ‣ Global Configuration.
Some older versions of NFS clients default to UDP instead of TCP and do not auto-negotiate for TCP. By default, FreeNAS® uses TCP. To support UDP connections, go to Services ‣ NFS and check the box Serve UDP NFS clients.
nfsstat -c or
nfsstat -s commands can be helpful
to detect problems from the Shell. A high proportion of retries
and timeouts compared to reads usually indicates network problems.
10.3. WebDAV Shares¶
In FreeNAS®, WebDAV shares can be created so that authenticated users can browse the contents of the specified volume, dataset, or directory from a web browser.
Configuring WebDAV shares is a two step process. First, create the WebDAV shares to specify which data can be accessed. Then, configure the WebDAV service by specifying the port, authentication type, and authentication password. Once the configuration is complete, the share can be accessed using a URL in the format:
- protocol: is either http or https, depending upon the Protocol configured in Services ‣ WebDAV.
- IP address: is the IP address or hostname of the FreeNAS® system. Take care when configuring a public IP address to ensure that the network’s firewall only allows access to authorized systems.
- port_number: is configured in Services ‣ WebDAV. If the FreeNAS® system is to be accessed using a public IP address, consider changing the default port number and ensure that the network’s firewall only allows access to authorized systems.
- share_name: is configured in Sharing ‣ WebDAV Shares.
Entering the URL in a web browser brings up an authentication pop-up message. Enter a username of webdav and the password configured in Services ‣ WebDAV.
At this time, only the webdav user is supported. For this reason, it is important to set a good password for this account and to only give the password to users which should have access to the WebDAV share.
To create a WebDAV share, click Sharing ‣ WebDAV Shares ‣ Add WebDAV Share which will open the screen shown in Figure 10.3.1.
Table 10.3.1 summarizes the available options.
|Share Path Name||string||input a name for the share|
|Path||browse button||browse to the volume/dataset to share|
|Read Only||checkbox||if checked, users cannot write to the share|
|Change User & Group Ownership||checkbox||if checked, automatically sets the share’s contents to the webdav user and group|
After clicking OK, a pop-up asks about enabling the service. Once the service starts, review the settings in Services ‣ WebDAV as they are used to determine which URL is used to access the WebDAV share and whether or not authentication is required to access the share. These settings are described in WebDAV.
10.4. Windows (SMB) Shares¶
FreeNAS® uses Samba to share volumes using Microsoft’s SMB protocol. SMB is built into the Windows and Mac OS X operating systems and most Linux and BSD systems pre-install the Samba client in order to provide support for SMB. If your distro did not, install the Samba client using the distro’s software repository.
The SMB protocol supports many different types of configuration scenarios, ranging from the very simple to quite complex. The complexity of the scenario depends upon the types and versions of the client operating systems that will connect to the share, whether the network has a Windows server, and whether Active Directory is being used. Depending on the authentication requirements, it might be necessary to create or import users and groups.
Samba supports server-side copy of files on the same share with clients from Windows 8 and higher. Copying between two different shares is not server-side. Windows 7 clients support server-side copying with Robocopy.
This chapter starts by summarizing the available configuration options. It demonstrates some common configuration scenarios as well as offering some troubleshooting tips. It is recommended to first read through this entire chapter before creating any SMB shares to get a better idea of the configuration scenario that best meets your network’s needs.
SMB Tips and Tricks shows helpful hints for configuring and managing SMB networking. The FreeNAS and Samba (CIFS) permissions and Advanced Samba (CIFS) permissions on FreeNAS videos clarify setting up permissions on SMB shares. Another helpful reference is Methods For Fine-Tuning Samba Permissions.
Run smbstatus from the Shell for a list of active connections and users.
Figure 10.4.1 shows the configuration screen that appears after clicking Sharing ‣ Windows (SMB Shares) ‣ Add Windows (SMB) Share.
Table 10.4.1 summarizes the options when creating a SMB share. Some settings are only available after clicking the Advanced Mode button. For simple sharing scenarios, Advanced Mode options are not needed. For more complex sharing scenarios, only change an Advanced Mode option after fully understanding the function of that option. smb.conf(5) provides more details for each configurable option.
|Path||browse button||select volume/dataset/directory to share|
|Use as home share||checkbox||check this box if the share is meant to hold user home directories; only one share can be the homes share|
|Name||string||mandatory; name of share|
|Apply Default Permissions||checkbox||sets the ACLs to allow read/write for owner/group and read-only for others; should only be unchecked when creating a share on a system that already has custom ACLs set|
|Export Read Only||checkbox||✓||prohibits write access to the share|
|Browsable to Network Clients||checkbox||✓||when checked, users see the contents of /homes (including other home directories of other users) and when unchecked, users see only their own home directory|
|Export Recycle Bin||checkbox||✓||deleted files are moved to a hidden
|Show Hidden Files||checkbox||✓||if enabled, the Windows hidden attribute is not set when filenames that begin with a dot (a Unix hidden file) are created; existing files are not affected|
|Allow Guest Access||checkbox||if checked, a password is not required to connect to the share; connections with a bad password are rejected unless the user account does not exist, in which case it is mapped to the guest account and granted the permissions of the guest user defined in the SMB service|
|Only Allow Guest Access||checkbox||✓||requires Allow guest access to also be checked; forces guest access for all connections|
|Access Based Share Enumeration||checkbox||✓||when checked, users can only see the shares they have permission to access; to change the default that grants Everyone access, use the computer management MMC on Windows or the sharesec command-line utility|
|Hosts Allow||string||✓||comma-, space-, or tab-delimited list of allowed hostnames or IP addresses|
|Hosts Deny||string||✓||comma-, space-, or tab-delimited list of denied hostnames or IP addresses; allowed hosts take precedence so can use ALL in this field and specify allowed hosts in Hosts Allow|
|VFS Objects||selection||✓||adds virtual file system modules to enhance functionality; Table 10.4.2 summarizes the available modules|
|Periodic Snapshot Task||drop-down menu||✓||used to configure directory shadow copies on a per-share basis; select the pre-configured periodic snapshot task to use for the share’s shadow copies; periodic snapshot must be recursive|
Note the following regarding some of the Advanced Mode settings:
- Hostname lookups add some time to accessing the SMB share. If you only use IP addresses, uncheck the Hostnames lookups box in Services ‣ SMB.
- When the Browsable to Network Clients box is checked (the default), the share is visible through Windows File Explorer or through net view. When the Use as a home share box is checked, unchecking the Browsable to Network Clients box hides the share named homes so that only the dynamically generated share containing the authenticated user’s home directory will be visible. By default, the homes share and the user’s home directory are both visible. Users are not automatically granted read or write permissions on browsable shares. This option provides no real security because shares that are not visible in Windows File Explorer can still be accessed with a UNC path.
- If some files on a shared volume should be hidden and inaccessible to users, put a veto files= line in the Auxiliary Parameters field. The syntax for the veto files option and some examples can be found in the smb.conf manual page.
Samba disables NTLMv1 authentication by default for security. Standard configurations of Windows XP and some configurations of later clients like Windows 7 will not be able to connect with NTLMv1 disabled. Security guidance for NTLMv1 and LM network authentication has information about the security implications and ways to enable NTLMv2 on those clients. If changing the client configuration is not possible, NTLMv1 authentication can be enabled by checking the box NTLMv1 auth in Services ‣ SMB.
Table 10.4.2 provides an overview of the available VFS modules. Be sure to research each module before adding or deleting it from the Selected column of the VFS Objects field of the share. Some modules need additional configuration after they are added. Refer to Stackable VFS modules and the vfs_* man pages for more details.
|acl_tdb||stores NTFS ACLs in a tdb file to enable full mapping of Windows ACLs|
|acl_xattr||stores NTFS ACLs in Extended Attributes (EAs) to enable the full mapping of Windows ACLs|
|aio_fork||enables async I/O|
|aio_pthread||implements async I/O in Samba vfs using a pthread pool instead of the internal Posix AIO interface|
|audit||logs share access, connects/disconnects, directory opens/creates/removes, and file opens/closes/renames/unlinks/chmods to syslog|
|cacheprime||primes the kernel file data cache|
|cap||translates filenames to and from the CAP encoding format, commonly used in Japanese language environments|
|catia||improves Mac interoperability by translating characters that are unsupported by Windows|
|commit||tracks the amount of data written to a file and synchronizes it to disk when a specified amount accumulates|
|crossrename||allows server side rename operations even if source and target are on different physical devices|
|default_quota||stores the default quotas that are reported to a windows client in the quota record of a user|
|dfs_samba4||distributed file system for providing an alternative name space, load balancing, and automatic failover|
|dirsort||sorts directory entries alphabetically before sending them to the client|
|expand_msdfs||enables support for Microsoft Distributed File System (DFS)|
|extd_audit||sends audit logs to both syslog and the Samba log files|
|fake_acls||stores file ownership and ACLs as extended attributes|
|fake_perms||allows roaming profile files and directories to be set as read-only|
|fruit||enhances OS X support by providing the SMB2 AAPL extension and Netatalk interoperability; automatically loads catia and streams_xattr but read the caveat in NOTE below table|
|full_audit||record selected client operations to the system log; if selected, a warning will indicate that Windows 10 clients may experience issues when transferring files to the NAS system when this module is enabled|
|linux_xfs_sgid||used to work around an old Linux XFS bug|
|media_harmony||allows Avid editorial workstations to share a network drive|
|netatalk||eases the co-existence of SMB and AFP shares|
|offline||marks all files in the share with the DOS offline attribute; this can prevent Windows Explorer from reading files just to make thumbnail images|
|posix_eadb||provides Extended Attributes (EAs) support so they can be used on filesystems which do not provide native support for EAs|
|preopen||useful for video streaming applications that want to read one file per frame|
|readahead||useful for Windows Vista clients reading data using Windows Explorer|
|readonly||marks a share as read-only for all clients connecting within the configured time period|
|shadow_copy||allows Microsoft shadow copy clients to browse shadow copies on Windows shares|
|shadow_copy_test||shadow copy testing|
|shell_snap||provides shell-script callouts for snapshot creation and deletion operations issued by remote clients using the File Server Remote VSS Protocol (FSRVP)|
|skel_opaque||implements dummy versions of all VFS modules (useful to VFS module developers)|
|skel_transparent||implements dummy passthrough functions of all VFS modules (useful to VFS module developers)|
|snapper||provides the ability for remote SMB clients to access shadow copies of FSRVP snapshots using Windows Explorer|
|streams_depot||experimental module to store alternate data streams in a central directory; the association with the primary file can be lost due to inode numbers changing when a directory is copied to a new location (see http://marc.info/?l=samba&m=132542069802160&w=2)|
|streams_xattr||enables storing of NTFS alternate data streams in the file system|
|syncops||ensures metadata operations are performed synchronously|
|time_audit||logs system calls that take longer than the number of defined milliseconds|
|unityed_media||allows multiple Avid clients to share a network drive|
|winmsa||emulate Microsoft’s MoveSecurityAttributes=0 registry option, setting the ACL for file and directory hierarchies to inherit from the parent directory into which they are moved|
|worm||controls the writability of files and folders depending on their change time and an adjustable grace period|
|xattr_tdb||stores Extended Attributes (EAs) in a tdb file so they can be used on filesystems which do not provide support for EAs|
|zfs_space||correctly calculates ZFS space used by the share, including space used by ZFS snapshots, quotas, and resevations; enabled by default|
|zfsacl||provide ACL extensions for proper integration with ZFS; enabled by default|
Be careful when using multiple SMB shares, some with and some without fruit. OS X clients negotiate SMB2 AAPL protocol extensions on the first connection to the server, so mixing shares with and without fruit will globally disable AAPL if the first connection occurs without fruit. To resolve this, all OS X clients need to disconnect from all SMB shares and the first reconnection to the server has to be to a fruit-enabled share.
These VFS objects do not appear in the selection box:
- recycle: moves deleted files to the recycle directory instead of deleting them. Controlled by Export Recycle Bin in the SMB share options.
- shadow_copy2: a more recent implementation of
shadow_copy with some additional features.
shadow_copy2 and the associated parameters are automatically added
smb4.confwhen a Periodic Snapshot Task is selected.
10.4.1. Configuring Unauthenticated Access¶
SMB supports guest logins, meaning that users can access the SMB share without needing to provide a username or password. This type of share is convenient as it is easy to configure, easy to access, and does not require any users to be configured on the FreeNAS® system. This type of configuration is also the least secure as anyone on the network can access the contents of the share. Additionally, since all access is as the guest user, even if the user inputs a username or password, there is no way to differentiate which users accessed or modified the data on the share. This type of configuration is best suited for small networks where quick and easy access to the share is more important than the security of the data on the share.
To configure an unauthenticated SMB share, click Wizard, then click the Next button twice to display the screen shown in Figure 10.4.2. Complete the following fields in this screen:
- Share name: enter a name for the share that is useful to you. In this example, the share is named smb_insecure.
- Click the button for Windows (SMB) and check the box for Allow Guest.
- Click the Ownership button. Click the drop-down User menu and select nobody. Click the Return button to return to the previous screen.
- Click the Add button. If you forget to do this, the share will not be created. Clicking the Add button adds an entry to the Name frame with the name that was entered in Share name.
Click the Next button twice, then the Confirm button to create the share. The Wizard automatically creates a dataset for the share and starts the SMB service so the share is immediately available. The new share is also be added to Sharing ‣ Windows (SMB).
Users can now access the share from any SMB client and will not be prompted for their username or password. For example, to access the share from a Windows system, open Explorer and click on Network. For this configuration example, a system named FREENAS appears with a share named insecure_smb. The user can copy data to and from the unauthenticated SMB share.
10.4.2. Configuring Authenticated Access Without a Domain Controller¶
Most configuration scenarios require each user to have their own user account and to authenticate before accessing the share. This allows the administrator to control access to data, provide appropriate permissions to that data, and to determine who accesses and modifies stored data. A Windows domain controller is not needed for authenticated SMB shares, which means that additional licensing costs are not required. However, since there is no domain controller to provide authentication for the network, each user account needs to be created on the FreeNAS® system. This type of configuration scenario is often used in home and small networks as it does not scale well if many users accounts are needed.
Before configuring this scenario, determine which users will need authenticated access. While not required for the configuration, it eases troubleshooting if the username and password that will be created on the FreeNAS® system matches that information on the client system. Next, determine if each user should have their own share to store their own data or if several users will be using the same share. The simpler configuration is to make one share per user as it does not require the creation of groups, adding the correct users to the groups, and ensuring that group permissions are set correctly.
To use the Wizard to create an authenticated SMB share, enter the following information, as shown in the example in Figure 10.4.3.
- Share name: enter a name for the share that is useful to you. In this example, the share is named smb_user1.
- Click the button for Windows (SMB).
- Click the Ownership button. To create the user account on the FreeNAS® system, type their name into the User field and check the Create User checkbox. The user’s password is then entered and confirmed. If the user will not be sharing this share with other users, type their name into the Group field and click Create Group. If, however, the share will be used by several users, instead type in a group name and check the Create Group box. In the example shown in Figure 10.4.4, user1 has been used for both the user and group name, meaning that this share will only be used by user1. When finished, click Return to return to the screen shown in Figure 10.4.3.
- Click the Add button. If you forget to do this, the share will not be created. Clicking the Add button adds an entry to the Name frame with the name that was entered in Share name.
If you wish to configure multiple authenticated shares, repeat for each user, giving each user their own Share name and Ownership. When finished, click Next twice, then Confirm to create the shares. The Wizard automatically creates a dataset with the correct ownership for each share and starts the SMB service so the shares are available immediately. The new shares are also added to Sharing ‣ Windows (SMB).
The authenticated share can now be tested from any SMB client. For example, to test an authenticated share from a Windows system, open Explorer and click on Network. For this configuration example, a system named FREENAS appears with a share named smb_user1. If you click on smb_user1, a Windows Security pop-up screen prompts for that user’s username and password. Enter the values that were configured for that share, in this case user user1. After authentication, the user can copy data to and from the SMB share.
To prevent Windows Explorer from hanging when accessing the share, map the share as a network drive. To do this, right-click the share and select Map network drive…. Choose a drive letter from the drop-down menu and click the Finish button.
Note that Windows systems cache a user’s credentials. This can cause issues when testing or accessing multiple authenticated shares as only one authentication is allowed at a time. If you are having problems authenticating to a share and are sure that you are entering the correct username and password, type cmd in the Search programs and files box and use the following command to see if you have already authenticated to a share. In this example, the user has already authenticated to the smb_user1 share:
net use New connections will be remembered. Status Local Remote Network ------------------------------------------------------------------------ OK \\FREENAS\smb_user1 Microsoft Windows Network The command completed successfully.
To clear the cache:
net use * /DELETE You have these remote connections: \\FREENAS\smb_user1 Continuing will cancel the connections. Do you want to continue this operation? <Y/N> [N]: y
An additional warning is shown if the share is currently open in Explorer:
There are open files and/or incomplete directory searches pending on the connection to \\FREENAS|smb_user1. Is it OK to continue disconnecting and force them closed? <Y/N> [N]: y The command completed successfully.
The next time a share is accessed with Explorer, you will be prompted to authenticate.
10.4.3. Configuring Shadow Copies¶
Shadow Copies, also known as the Volume Shadow Copy Service (VSS) or Previous Versions, is a Microsoft service for creating volume snapshots. Shadow copies allow you to easily restore previous versions of files from within Windows Explorer. Shadow Copy support is built into Vista and Windows 7. Windows XP or 2000 users need to install the Shadow Copy client.
When you create a periodic snapshot task on a ZFS volume that is configured as a SMB share in FreeNAS®, it is automatically configured to support shadow copies.
Before using shadow copies with FreeNAS®, be aware of the following caveats:
- If the Windows system is not fully patched to the latest service pack, Shadow Copies may not work. If you are unable to see any previous versions of files to restore, use Windows Update to make sure that the system is fully up-to-date.
- Shadow copy support only works for ZFS pools or datasets. This means that the SMB share must be configured on a volume or dataset, not on a directory.
- Datasets are filesystems and shadow copies cannot traverse filesystems. If you want to be able to see the shadow copies in your child datasets, create separate shares for them.
- Shadow copies will not work with a manual snapshot, you must create a periodic snapshot task for the pool or dataset being shared by SMB or a recursive task for a parent dataset.
- The periodic snapshot task should be created and at least one snapshot should exist before creating the SMB share. If the SMB share was created first, restart the SMB service in Services ‣ Control Services.
- Appropriate permissions must be configured on the volume/dataset being shared by SMB.
- Users cannot delete shadow copies on the Windows system due to the way Samba works. Instead, the administrator can remove snapshots from the FreeNAS® administrative GUI. The only way to disable shadow copies completely is to remove the periodic snapshot task and delete all snapshots associated with the SMB share.
To configure shadow copy support, use the instructions in Configuring Authenticated Access Without a Domain Controller to create the desired number of shares. In this configuration example, a Windows 7 computer has two users: user1 and user2. For this example, two authenticated shares are created so that each user account has their own share. The first share is named user1 and the second share is named user2. Then:
Storage ‣ Periodic Snapshot Tasks
‣ Add Periodic Snapshot
to create at least one periodic snapshot task. You can either
create a snapshot task for each user’s dataset, in this example the
/mnt/volume1/user2, or you can create one periodic snapshot task for the entire volume, in this case
/mnt/volume1. Before continuing to the next step, confirm that at least one snapshot for each defined task is displayed in the Storage ‣ Snapshots tab. When creating the schedule for the periodic snapshot tasks, keep in mind how often your users need to access modified files and during which days and time of day they are likely to make changes.
- Go to
Sharing ‣ Windows (SMB) Shares.
Highlight a share and click Edit, then
Advanced Mode. Click the
Periodic Snapshot Task drop-down menu and select the
periodic snapshot task to use for that share. Repeat for each share
being configured as a shadow copy. For this example, the share
/mnt/volume1/user1is configured to use a periodic snapshot task that was configured to take snapshots of the
/mnt/volume1/user1dataset and the share named
/mnt/volume1/user2is configured to use a periodic snapshot task that was configured to take snapshots of the
- Verify that the SMB service is set to ON in Services ‣ Control Services.
Figure 10.4.5 provides an example of using shadow copies while logged in as user1 on the Windows system. In this example, the user right-clicked modified file and selected Restore previous versions from the menu. This particular file has three versions: the current version, plus two previous versions stored on the FreeNAS® system. The user can choose to open one of the previous versions, copy a previous version to the current folder, or restore one of the previous versions, overwriting the existing file on the Windows system.
10.5. Block (iSCSI)¶
iSCSI is a protocol standard for the consolidation of storage data. iSCSI allows FreeNAS® to act like a storage area network (SAN) over an existing Ethernet network. Specifically, it exports disk devices over an Ethernet network that iSCSI clients (called initiators) can attach to and mount. Traditional SANs operate over fibre channel networks which require a fibre channel infrastructure such as fibre channel HBAs, fibre channel switches, and discrete cabling. iSCSI can be used over an existing Ethernet network, although dedicated networks can be built for iSCSI traffic in an effort to boost performance. iSCSI also provides an advantage in an environment that uses Windows shell programs; these programs tend to filter “Network Location” but iSCSI mounts are not filtered.
Before configuring the iSCSI service, be familiar with this iSCSI terminology:
CHAP: an authentication method which uses a shared secret and three-way authentication to determine if a system is authorized to access the storage device and to periodically confirm that the session has not been hijacked by another system. In iSCSI, the initiator (client) performs the CHAP authentication.
Mutual CHAP: a superset of CHAP in that both ends of the communication authenticate to each other.
Initiator: a client which has authorized access to the storage data on the FreeNAS® system. The client requires initiator software to initiate the connection to the iSCSI share.
Target: a storage resource on the FreeNAS® system. Every target has a unique name known as an iSCSI Qualified Name (IQN).
Internet Storage Name Service (iSNS): protocol for the automated discovery of iSCSI devices on a TCP/IP network.
Extent: the storage unit to be shared. It can either be a file or a device.
Portal: indicates which IP addresses and ports to listen on for connection requests.
LUN: Logical Unit Number representing a logical SCSI device. An initiator negotiates with a target to establish connectivity to a LUN. The result is an iSCSI connection that emulates a connection to a SCSI hard disk. Initiators treat iSCSI LUNs as if they were a raw SCSI or SATA hard drive. Rather than mounting remote directories, initiators format and directly manage filesystems on iSCSI LUNs. When configuring multiple iSCSI LUNs, create a new target for each LUN. Since iSCSI multiplexes a target with multiple LUNs over the same TCP connection, there can be TCP contention when more than one target accesses the same LUN. FreeNAS® supports up to 1024 LUNs.
In FreeNAS®, iSCSI is built into the kernel. This version of iSCSI supports Microsoft Offloaded Data Transfer (ODX), meaning that file copies happen locally, rather than over the network. It also supports the VAAI (vStorage APIs for Array Integration) primitives for efficient operation of storage tasks directly on the NAS. To take advantage of the VAAI primitives, create a zvol using the instructions in Create zvol and use it to create a device extent, as described in Extents.
To configure iSCSI:
- Review the target global configuration parameters.
- Create at least one portal.
- Determine which hosts are allowed to connect using iSCSI and create an initiator.
- Decide if authentication will be used, and if so, whether it will be CHAP or mutual CHAP. If using authentication, create an authorized access.
- Create a target.
- Create either a device or a file extent to be used as storage.
- Associate a target with an extent.
- Start the iSCSI service in Services ‣ Control Services.
The rest of this section describes these steps in more detail.
10.5.1. Target Global Configuration¶
Sharing ‣ Block (iSCSI) ‣ Target Global Configuration, shown in Figure 10.5.1, contains settings that apply to all iSCSI shares. Table 10.5.1 summarizes the settings that can be configured in the Target Global Configuration screen.
Some built-in values affect iSNS usage. Fetching of allowed initiators from iSNS is not implemented, so target ACLs must be configured manually. To make iSNS registration useful, iSCSI targets should have explicitly configured port IP addresses. This avoids initiators attempting to discover unconfigured target portal addresses like 0.0.0.0.
The iSNS registration period is 900 seconds. Registered Network Entities not updated during this period are unregistered. The timeout for iSNS requests is 5 seconds.
|Base Name||string||see the “Constructing iSCSI names using the iqn. format” section of RFC 3721 if unfamiliar with this format|
|ISNS Servers||string||space delimited list of hostnames or IP addresses of ISNS servers with which to register the system’s iSCSI targets and portals|
|Pool Available Space Threshold||integer||enter the percentage of free space that should remain in the pool; when this percentage is reached, the system issues an alert, but only if zvols are used; see VAAI Threshold Warning|
A portal specifies the IP address and port number to be used for iSCSI connections. Sharing ‣ Block (iSCSI) ‣ Portals ‣ Add Portal brings up the screen shown in Figure 10.5.2.
Table 10.5.2 summarizes the settings that can be configured when adding a portal. If you need to assign additional IP addresses to the portal, click the link Add extra Portal IP.
|Comment||string||optional description; portals are automatically assigned a numeric group ID|
|Discovery Auth Method||drop-down menu||configures the authentication level required by the target for discovery of valid devices, where None will allow anonymous discovery while CHAP and Mutual CHAP require authentication|
|Discovery Auth Group||drop-down menu||select a user created in Authorized Access if the Discovery Auth Method is set to CHAP or Mutual CHAP|
|IP address||drop-down menu||select the IP address associated with an interface or the wildcard address of 0.0.0.0 (any interface)|
|Port||integer||TCP port used to access the iSCSI target; default is 3260|
FreeNAS® systems with multiple IP addresses or interfaces can use a portal to provide services on different interfaces or subnets. This can be used to configure multi-path I/O (MPIO). MPIO is more efficient than a link aggregation.
If the FreeNAS® system has multiple configured interfaces, portals can also be used to provide network access control. For example, consider a system with four interfaces configured with the following addresses:
You could create a portal containing the first two IP addresses (group ID 1) and a portal containing the remaining two IP addresses (group ID 2). You could then create a target named A with a Portal Group ID of 1 and a second target named B with a Portal Group ID of 2. In this scenario, the iSCSI service would listen on all four interfaces, but connections to target A would be limited to the first two networks and connections to target B would be limited to the last two networks.
Another scenario would be to create a portal which includes every IP address except for the one used by a management interface. This would prevent iSCSI connections to the management interface.
The next step is to configure authorized initiators, or the systems which are allowed to connect to the iSCSI targets on the FreeNAS® system. To configure which systems can connect, use Sharing ‣ Block (iSCSI) ‣ Initiators ‣ Add Initiator, shown in Figure 10.5.3.
Table 10.5.3 summarizes the settings that can be configured when adding an initiator.
|Initiators||string||use ALL keyword or a list of initiator hostnames separated by spaces|
|Authorized network||string||use ALL keyword or a network address with CIDR mask such as 192.168.2.0/24|
In the example shown in Figure 10.5.4, two groups have been created. Group 1 allows connections from any initiator on any network. Group 2 allows connections from any initiator on the 10.10.1.0/24 network. Click an initiator’s entry to display its Edit and Delete buttons.
Attempting to delete an initiator causes a warning that indicates if any targets or target/extent mappings depend upon the initiator. Confirming the delete causes these to be deleted also.
10.5.4. Authorized Accesses¶
If you will be using CHAP or mutual CHAP to provide authentication, you must create an authorized access in Sharing ‣ Block (iSCSI) ‣ Authorized Accesses ‣ Add Authorized Access. This screen is shown in Figure 10.5.5.
This screen sets login authentication. This is different from discovery authentication which is set in Target Global Configuration.
Table 10.5.4 summarizes the settings that can be configured when adding an authorized access:
|Group ID||integer||allows different groups to be configured with different authentication profiles; for instance, all users with a Group ID of 1 will inherit the authentication profile associated with Group 1|
|User||string||name of user account to create for CHAP authentication with the user on the remote system; many initiators default to using the initiator name as the user|
|Secret||string||password to be associated with User; the iSCSI standard requires that this be between 12 and 16 characters|
|Peer User||string||only input when configuring mutual CHAP; in most cases it will need to be the same value as User|
|Peer Secret||string||the mutual secret password which must be different than the Secret; required if Peer User is set|
CHAP does not work with GlobalSAN initiators on Mac OS X.
As authorized accesses are added, they will be listed under View Authorized Accesses. In the example shown in Figure 10.5.6, three users (test1, test2, and test3) and two groups (1 and 2) have been created, with group 1 consisting of one CHAP user and group 2 consisting of one mutual CHAP user and one CHAP user. Click an authorized access entry to display its Edit and Delete buttons.
Next, create a Target using Sharing ‣ Block (iSCSI) ‣ Targets ‣ Add Target, as shown in Figure 10.5.7. A target combines a portal ID, allowed initiator ID, and an authentication method. Table 10.5.5 summarizes the settings that can be configured when creating a Target.
An iSCSI target creates a block device that may be accessible to multiple initiators. A clustered filesystem is required on the block device, such as VMFS used by VMware ESX/ESXi, in order for multiple initiators to mount the block device read/write. If a traditional filesystem such as EXT, XFS, FAT, NTFS, UFS, or ZFS is placed on the block device, care must be taken that only one initiator at a time has read/write access or the result will be filesystem corruption. If multiple clients need access to the same data on a non-clustered filesystem, use SMB or NFS instead of iSCSI, or create multiple iSCSI targets (one per client).
|Target Name||string||required value; base name will be appended automatically if it does not start with iqn|
|Target Alias||string||optional user-friendly name|
|Portal Group ID||drop-down menu||leave empty or select number of existing portal to use|
|Initiator Group ID||drop-down menu||select which existing initiator group has access to the target|
|Auth Method||drop-down menu||choices are None, Auto, CHAP, or Mutual CHAP|
|Authentication Group number||drop-down menu||None or integer representing number of existing authorized access|
iSCSI targets provide virtual access to resources on the FreeNAS® system. Extents are used to define resources to share with clients. There are two types of extents: device and file.
Device extents provide virtual storage access to zvols, zvol snapshots, or physical devices like a disk, an SSD, a hardware RAID volume, or a HAST device.
File extents provide virtual storage access to an individual file.
For typical use as storage for virtual machines where the virtualization software is the iSCSI initiator, device extents with zvols provide the best performance and most features. For other applications, device extents sharing a raw device can be appropriate. File extents do not have the performance or features of device extents, but do allow creating multiple extents on a single filesystem.
Virtualized zvols support all the FreeNAS® VAAI primitives and are recommended for use with virtualization software as the iSCSI initiator.
The ATS, WRITE SAME, XCOPY and STUN, primitives are supported by both file and device extents. The UNMAP primitive is supported by zvols and raw SSDs. The threshold warnings primitive is fully supported by zvols and partially supported by file extents.
Virtualizing a raw device like a single disk or hardware RAID volume limits performance to the abilities of the device. Because this bypasses ZFS, such devices do not benefit from ZFS caching or provide features like block checksums or snapshots.
Virtualizing a zvol adds the benefits of ZFS, such as read and write cache. Even if the client formats a device extent with a different filesystem, the data still resides on a ZFS volume and benefits from ZFS features like block checksums and snapshots.
For performance reasons and to avoid excessive fragmentation, keep the used space of the pool below 50% when using iSCSI. The capacity of an existing extent can be increased as shown in Growing LUNs.
To add an extent, go to
Sharing ‣ Block (iSCSI) ‣ Extents ‣ Add Extent.
In the example shown in
the device extent is using the
export zvol that was previously
created from the
Table 10.5.6 summarizes the settings that can be configured when creating an extent. Note that file extent creation will fail if you do not append the name of the file to be created to the volume/dataset name.
|Extent Name||string||name of extent; if the Extent size is not 0, it cannot be an existing file within the volume/dataset|
|Extent Type||drop-down menu||select from File or Device|
|Device||drop-down menu||only appears if Device is selected; select the unformatted disk, controller, zvol, zvol snapshot, or HAST device|
|Serial||string||unique LUN ID; the default is generated from the system’s MAC address|
|Path to the extent||browse button||only appears if File is selected; browse to an existing file and use 0 as the Extent size, or browse to the volume or dataset, click Close, append the Extent Name to the path, and specify a value in Extent size; extents cannot be created inside the jail root directory|
|Extent size||integer||only appears if File is selected; if the size is specified as 0, the file must already exist and the actual file size will be used; otherwise, specify the size of the file to create|
|Logical Block Size||drop-down menu||only override the default if the initiator requires a different block size|
|Disable Physical Block Size Reporting||checkbox||if the initiator does not support physical block size values over 4K (MS SQL), check this box|
|Available Space Threshold||string||only appears if File or a zvol is selected; when the specified percentage of free space is reached, the system issues an alert; see VAAI Threshold Warning|
|Enable TPC||checkbox||if checked, an initiator can bypass normal access control and access any scannable target; this allows xcopy operations otherwise blocked by access control|
|Xen initiator compat mode||checkbox||check this box when using Xen as the iSCSI initiator|
|LUN RPM||drop-down menu||do NOT change this setting when using Windows as the initiator; only needs to be changed in large environments where the number of systems using a specific RPM is needed for accurate reporting statistics|
|Read-only||checkbox||check this box to prevent the initiator from initializing this LUN|
The last step is associating an extent to a target within Sharing ‣ Block (iSCSI) ‣ Associated Targets ‣ Add Target/Extent. This screen is shown in Figure 10.5.9. Use the drop-down menus to select the existing target and extent. Click OK to add an entry for the LUN.
Table 10.5.7 summarizes the settings that can be configured when associating targets and extents.
|Target||drop-down menu||select the pre-created target|
|LUN ID||drop-down menu||select the value to use or type in a value between 1 and 1023; note that some initiators expect a value below 256|
|Extent||drop-down menu||select the pre-created extent|
It is recommended to always associate extents to targets in a one-to-one manner, even though the GUI will allow multiple extents to be associated with the same target.
Each LUN entry has Edit and Delete buttons for modifying the settings or deleting the LUN entirely. A verification popup appears when the Delete button is clicked. If an initiator has an active connection to the LUN, it is indicated in red text. It is recommended to clear initiator connections to a LUN before deleting it.
After iSCSI has been configured, remember to start it in Services ‣ Control Services. Click the red OFF button next to iSCSI. After a second or so, it will change to a blue ON, indicating that the service has started.
10.5.8. Connecting to iSCSI¶
To access the iSCSI target, clients must use iSCSI initiator software.
An iSCSI Initiator client is pre-installed with Windows 7. A detailed how-to for this client can be found here. A client for Windows 2000, XP, and 2003 can be found here. This how-to shows how to create an iSCSI target for a Windows 7 system.
Mac OS X does not include an initiator. globalSAN is a commercial, easy-to-use Mac initiator.
BSD systems provide command line initiators: iscontrol(8) comes with FreeBSD versions 9.x and lower, iscsictl(8) comes with FreeBSD versions 10.0 and higher, iscsi-initiator(8) comes with NetBSD, and iscsid(8) comes with OpenBSD.
Some Linux distros provide the command line utility iscsiadm from Open-iSCSI. Use a web search to see if a package exists for your distribution should the command not exist on your Linux system.
If a LUN is added while iscsiadm is already connected, it will not see the new LUN until rescanned with iscsiadm -m node -R. Alternately, use iscsiadm -m discovery -t st -p portal_IP to find the new LUN and iscsiadm -m node -T LUN_Name -l to log into the LUN.
Instructions for connecting from a VMware ESXi Server can be found at How to configure FreeNAS 8 for iSCSI and connect to ESX(i). Note that the requirements for booting vSphere 4.x off iSCSI differ between ESX and ESXi. ESX requires a hardware iSCSI adapter while ESXi requires specific iSCSI boot firmware support. The magic is on the booting host side, meaning that there is no difference to the FreeNAS® configuration. See the iSCSI SAN Configuration Guide for details.
The VMware firewall only allows iSCSI connections on port 3260 by default. If a different port has been selected, outgoing connections to that port must be manually added to the firewall before those connections will work.
If the target can be seen but does not connect, check the Discovery Auth settings in Target Global Configuration.
If the LUN is not discovered by ESXi, make sure that promiscuous mode is set to Accept in the vSwitch.
10.5.9. Growing LUNs¶
The method used to grow the size of an existing iSCSI LUN depends on whether the LUN is backed by a file extent or a zvol. Both methods are described in this section.
Enlarging a LUN with one of the methods below gives it more unallocated space, but does not automatically resize filesystems or other data on the LUN. This is the same as binary-copying a smaller disk onto a larger one. More space is available on the new disk, but the partitions and filesystems on it must be expanded to use this new space. Resizing virtual disk images is usually done from virtual machine management software. Application software to resize filesystems is dependent on the type of filesystem and client, but is often run from within the virtual machine. For instance, consider a Windows VM with the last partition on the disk holding an NTFS filesystem. The LUN is expanded and the partition table edited to add the new space to the last partition. The Windows disk manager must still be used to resize the NTFS filesystem on that last partition to use the new space.
10.5.9.1. Zvol Based LUN¶
To grow a zvol based LUN, go to Storage ‣ Volumes ‣ View Volumes, highlight the zvol to be grown, and click Edit zvol. In the example shown in Figure 10.5.10, the current size of the zvol named zvol1 is 4GB.
Enter the new size for the zvol in the Size field and click Edit ZFS Volume. This menu closes and the new size for the zvol is immediately shown in the Used column of the View Volumes screen.
The GUI does not allow reducing (shrinking) the size of the zvol, as doing so could result in loss of data. It also does not allow increasing the size of the zvol past 80% of the volume size.
10.5.9.2. File Extent Based LUN¶
To grow a file extent based LUN, go to
Services ‣ iSCSI ‣ File Extents
‣ View File Extents to determine the path of the file extent to
grow. Open Shell to grow the extent. This example
/mnt/volume1/data by 2 G:
truncate -s +2g /mnt/volume1/data
Go back to Services ‣ iSCSI ‣ File Extents ‣ View File Extents and click the Edit button for the file extent. Set the size to 0 as this causes the iSCSI target to use the new size of the file.