7. Storage¶

7.1.1. Volume Manager¶

If you have unformatted disks or wish to overwrite the current filesystem and data on your disks, use Volume Manager to format the disks into a ZFS pool. If you have multiple disks and are new to how ZFS handles redundancy, please see the ZFS Primer before using Volume Manager.

Selecting Storage → Volumes → Volume Manager opens a screen like the example shown in Figure 7.1.1.

Fig. 7.1.1 Creating a ZFS Pool Using Volume Manager

Table 7.1.1 summarizes the configuration options of this screen.

Drag the slider to select the desired number of disks. Volume Manager will display the resulting storage capacity, taking swap space into account. To change the layout or the number of disks, use the mouse to drag the slider to the desired volume layout. The Volume layout drop-down menu can also be clicked if a different level of redundancy is required.

Volume Manager only allows choosing a configuration if enough disks have been selected to create that configuration. These layouts are supported:

• Stripe: requires at least one disk
• Mirror: requires at least two disks
• RAIDZ1: requires at least three disks
• RAIDZ2: requires at least four disks
• RAIDZ3: requires at least five disks
• log device: requires at least one dedicated device, SSD is recommended
• cache device: requires at least one dedicated device, SSD is recommended

If you have more than five disks and are using ZFS, consider the number of disks to use for best performance and scalability. An overview of the recommended disk group sizes as well as more information about log and cache devices can be found in the ZFS Primer.

The Add Volume button warns that existing data will be cleared. In other words, creating a new volume reformats the selected disks. If your intent is to not overwrite the data on an existing volume, click the Cancel button and refer to Import Disk and Import Volume to see if the existing format is supported. If so, perform that supported action instead. If the current storage format is not supported, it is necessary to back up the data to external media, format the disks, then restore the data to the new volume.

Depending upon the size and number of disks, the type of controller, and whether encryption is selected, creating the volume may take some time. After the volume is created, the screen will refresh and the new volume will be listed in the tree under Storage → Volumes. Click the + next to the volume name to access its Change Permissions, Create Dataset, and Create zvol options.

7.1.1.2. Manual Setup¶

The Manual Setup button shown in Figure 7.1.1 can be used to create a non-optimal ZFS volume. While this is not recommended, it can, for example, be used to create a volume containing disks of different sizes.

Note

When using disks of differing sizes, the volume is limited by the size of the smallest disk. For this reason, it is recommended to instead use Volume Manager with same-size disks.

Figure 7.1.2 shows the Manual Setup screen and Table 7.1.2 summarizes the available options.

Fig. 7.1.2 Creating a Non-Optimal ZFS Volume

Table 7.1.2 Manual Setup Options¶

Setting	Value	Description
Volume name	string	ZFS volumes must conform to these naming conventions ; it is recommended to choose a name that will stick out in the logs (e.g. not data or freenas)
Encryption	checkbox	read the section on Encryption before choosing to use encryption
Member disks	list	highlight desired number of disks from list of available disks
Deduplication	drop-down menu	do not change this setting unless instructed to do so by your iXsystems support engineer
ZFS Extra	bullet selection	used to specify if disk is used for storage (None), a log device, a cache device, or a spare

7.1.2. Change Permissions¶

Setting permissions is an important aspect of configuring volumes. The graphical administrative interface is meant to set the initial permissions for a volume or dataset in order to make it available as a share. Once a share is available, the client operating system should be used to fine-tune the permissions of the files and directories that are created by the client.

The chapter on Sharing contains configuration examples for several types of permission scenarios. This section provides an overview of the screen that is used to set permissions.

After a volume or dataset is created, it is listed by its mount point name in Storage → Volumes → View Volumes. Clicking the Change Permissions icon for a specific volume/dataset displays the screen shown in Figure 7.1.3. Table 7.1.3 summarizes the options in this screen.

Fig. 7.1.3 Changing Permissions on a Volume or Dataset

If a mix of operating systems or clients will be accessing the volume/dataset using a non-CIFS share, select the Unix Permission Type, as all clients understand them.

The Windows Permission Type augments traditional Unix permissions with ACLs. Use the Windows Permission Type for CIFS shares or when the TrueNAS® system is a member of an Active Directory domain.

If you change your mind about the Permission Type, it is not necessary to recreate the volume/dataset, as existing data is not lost. However, changing from Windows to Unix or Mac will remove the extended permissions provided by ACLs from existing files.

When the Windows Permission Type is set, the ACLs are set to what Windows sets on new files and directories by default. The Windows client should then be used to fine-tune the permissions as required.

7.1.3. Create Dataset¶

An existing ZFS volume can be divided into datasets. Permissions, compression, deduplication, and quotas can be set on a per-dataset basis, allowing more granular control over access to storage data. A dataset is similar to a folder in that you can set permissions; it is also similar to a filesystem in that you can set properties such as quotas and compression as well as create snapshots.

Selecting an existing ZFS volume in the tree and clicking Create Dataset shows the screen in Figure 7.1.4.

Fig. 7.1.4 Creating a ZFS Dataset

Table 7.1.4 summarizes the options available when creating a ZFS dataset. Some settings are only available in Advanced Mode. To see these settings, either click the Advanced Mode button, or configure the system to always display these settings by checking the box Show advanced fields by default in System → Advanced. Most attributes, except for the Dataset Name, Case Sensitivity, and Record Size, can be changed after dataset creation by highlighting the dataset name and clicking its Edit Options button in Storage → Volumes → View Volumes.

After a dataset is created, you can click on that dataset and select Create Dataset, thus creating a nested dataset, or a dataset within a dataset. A zvol can also be created within a dataset. When creating datasets, double-check that you are using the Create Dataset option for the intended volume or dataset. If you get confused when creating a dataset on a volume, click all existing datasets to close them–the remaining Create Dataset will be for the volume.

7.1.4. Create zvol¶

A zvol is a feature of ZFS that creates a raw block device over ZFS. This allows you to use a zvol as an iSCSI device extent.

To create a zvol, select an existing ZFS volume or dataset from the tree then click Create zvol to open the screen shown in Figure 7.1.5.

Fig. 7.1.5 Creating a zvol

The configuration options are described in Table 7.1.5. Some settings are only available in Advanced Mode. To see these settings, either click the Advanced Mode button or configure the system to always display these settings by checking Show advanced fields by default in System → Advanced.

7.1.5. Import Disk¶

The Volume → Import Disk screen, shown in Figure 7.1.6, is used to import a single disk that has been formatted with the UFS, NTFS, MSDOS, or EXT2 filesystem. The import is meant to be a temporary measure to copy the data from a disk to an existing ZFS dataset. Only one disk can be imported at a time.

Fig. 7.1.6 Importing a Disk

Use the drop-down menu to select the disk to import, select the type of filesystem on the disk, and browse to the ZFS dataset that will hold the copied data. When you click Import Volume, the disk is mounted, its contents are copied to the specified ZFS dataset, and the disk is unmounted after the copy operation completes.

7.1.6. Import Volume¶

If you click Storage → Volumes → Import Volume, you can configure TrueNAS® to use an existing ZFS pool. This action is typically performed when an existing TrueNAS® system is re-installed. Since the operating system is separate from the storage disks, a new installation does not affect the data on the disks. However, the new operating system needs to be configured to use the existing volume.

Figure 7.1.7 shows the initial pop-up window that appears when you import a volume.

Fig. 7.1.7 Initial Import Volume Screen

If you are importing an unencrypted ZFS pool, select No: Skip to import to open the screen shown in Figure 7.1.8.

Fig. 7.1.8 Importing a Non-Encrypted Volume

Existing volumes should be available for selection from the drop-down menu. In the example shown in Figure 7.1.8, the TrueNAS® system has an existing, unencrypted ZFS pool. Once the volume is selected, click the OK button to import the volume.

If an existing ZFS pool does not show in the drop-down menu, run zpool import from Shell to import the pool.

If you plan to physically install ZFS formatted disks from another system, be sure to export the drives on that system to prevent an “in use by another machine” error during the import.

7.1.6.1. Importing an Encrypted Pool¶

If you are importing an existing GELI-encrypted ZFS pool, you must decrypt the disks before importing the pool. In Figure 7.1.7, select Yes: Decrypt disks to access the screen shown in Figure 7.1.9.

Fig. 7.1.9 Decrypting Disks Before Importing a ZFS Pool

Select the disks in the encrypted pool, browse to the location of the saved encryption key, input the passphrase associated with the key, then click OK to decrypt the disks.

Note

The encryption key is required to decrypt the pool. If the pool cannot be decrypted, it cannot be re-imported after a failed upgrade or lost configuration. This means that it is very important to save a copy of the key and to remember the passphrase that was configured for the key. Refer to Managing Encrypted Volumes for instructions on how to manage the keys for encrypted volumes.

Once the pool is decrypted, it will appear in the drop-down menu of Figure 7.1.8. Click the OK button to finish the volume import.

7.1.7. View Disks¶

Storage → Volumes → View Disks shows all of the disks recognized by the TrueNAS® system. An example is shown in Figure 7.1.10.

Fig. 7.1.10 Viewing Disks

The current configuration of each device is displayed. Click a disk’s entry and then its Edit button to change its configuration. The configurable options are described in Table 7.1.6.

Clicking a disk’s entry will also display its Wipe button which can be used to blank a disk while providing a progress bar of the wipe’s status. Use this option before discarding a disk.

7.1.8. View Enclosure¶

Click Storage → Volumes → View Enclosure to receive a status summary of the appliance’s disks and hardware. An example is shown in Figure 7.1.11.

Fig. 7.1.11 View Enclosure

This screen is divided into the following sections:

Array Device Slot: has an entry for each slot in the storage array, indicating the disk’s current status and FreeBSD device name. To blink the status light for that disk as a visual indicator, click its Identify button.

Cooling: has an entry for each fan, its status, and its RPM.

Enclosure: shows the status of the enclosure.

Power Supply: shows the status of each power supply.

SAS Expander: shows the status of the expander.

Temperature Sensor: shows the current temperature of each expander and the disk chassis.

Voltage Sensor: shows the current voltage for each sensor, VCCP, and VCC.

7.1.9. View Volumes¶

Storage → Volumes → View Volumes is used to view and further configure existing ZFS pools, datasets, and zvols. The example shown in Figure 7.1.12 shows one ZFS pool (volume1) with two datasets (the one automatically created with the pool, volume1, and dataset1) and one zvol (zvol1).

Note that in this example, there are two datasets named volume1. The first represents the ZFS pool and its Used and Available entries reflect the total size of the pool, including disk parity. The second represents the implicit or root dataset and its Used and Available entries indicate the amount of disk space available for storage.

Buttons are provided for quick access to Volume Manager, Import Disk, Import Volume, and View Disks. If the system has multipath-capable hardware, an extra button will be added, View Multipaths. For each entry, the columns indicate the Name, how much disk space is Used, how much disk space is Available, the type of Compression, the Compression Ratio, the Status, and whether it is mounted as read-only.

Fig. 7.1.12 Viewing Volumes

Clicking the entry for a pool causes several buttons to appear at the bottom of the screen. The buttons perform these actions:

Detach Volume: allows you to either export the pool or to delete the contents of the pool, depending upon the choice you make in the screen shown in Figure 7.1.13. The Detach Volume screen displays the current used space and indicates if there are any shares, provides checkboxes to Mark the disks as new (destroy data) and to Also delete the share’s configuration, asks if you are sure that you want to do this, and the browser will turn red to alert you that you are about to do something that will make the data inaccessible. If you do not check the box to mark the disks as new, the volume will be exported. This means that the data is not destroyed and the volume can be re-imported at a later time. If you will be moving a ZFS pool from one system to another, perform this export action first as it flushes any unwritten data to disk, writes data to the disk indicating that the export was done, and removes all knowledge of the pool from the system. If you do check the box to mark the disks as new, the pool and all the data in its datasets, zvols, and shares will be destroyed and the underlying disks will be returned to their raw state.

Fig. 7.1.13 Detach or Delete a Volume

Scrub Volume: scrubs and how to schedule them are described in more detail in Scrubs. This button allows you to manually initiate a scrub. Since a scrub is I/O intensive and can negatively impact performance, you should not initiate one while the system is busy. A Cancel button is provided to cancel a scrub. If a scrub is cancelled, the next scrub will start over from the beginning, not where the cancelled scrub left off. To view the current status of a running scrub or the statistics from the last completed scrub, click the Volume Status button.

Volume Status: as shown in the example in Figure 7.1.14, this screen shows the device name and status of each disk in the ZFS pool as well as any read, write, or checksum errors. It also indicates the status of the latest ZFS scrub. Clicking the entry for a device causes buttons to appear to edit the device’s options (shown in Figure 7.1.15), offline or online the device, or replace the device (as described in Replacing a Failed Drive).

Upgrade: used to upgrade the pool to the latest ZFS features, as described in Upgrading a ZFS Pool. This button will not appear if the pool is running the latest versions of feature flags.

Fig. 7.1.14 Volume Status

Selecting a disk in Volume Status and clicking its Edit Disk button shows the screen in Figure 7.1.15. Table 7.1.6 summarizes the configurable options.

Fig. 7.1.15 Editing a Disk

Clicking a dataset in Storage → Volumes → View Volumes causes buttons to appear at the bottom of the screen, providing these options:

Change Permissions: edit the dataset’s permissions as described in Change Permissions.

Create Snapshot: create a one-time snapshot. To schedule the regular creation of snapshots, instead use Periodic Snapshot Tasks.

Destroy Dataset: clicking the Destroy Dataset button causes the browser window to turn red to indicate that this is a destructive action. The Destroy Dataset screen forces you to check the box I’m aware this will destroy all child datasets and snapshots within this dataset before it will perform this action.

Edit Options: edit the volume’s properties described in Table 7.1.4. Note that it will not allow changing the dataset’s name.

Create Dataset: used to create a child dataset within this dataset.

Create zvol: create a child zvol within this dataset.

Clicking a zvol in Storage → Volumes → View Volumes causes icons to appear at the bottom of the screen: Create Snapshot, Edit zvol, and Destroy zvol. Similar to datasets, a zvol’s name cannot be changed, and destroying a zvol requires confirmation.

7.1.9.1. Managing Encrypted Volumes¶

If the Encryption box is checked during the creation of a pool, additional buttons appear in the entry for the pool in Storage → Volumes → View Volumes. An example is shown in Figure 7.1.16.

Fig. 7.1.16 Encryption Icons Associated with an Encrypted Pool

These additional encryption buttons are used to:

Create/Change Passphrase: click this button to set and confirm the passphrase associated with the GELI encryption key. You will be prompted to enter and repeat the desired passphrase and a red warning reminds you to Remember to add a new recovery key as this action invalidates the previous recovery key. Unlike a password, a passphrase can contain spaces and is typically a series of words. A good passphrase is easy to remember (like the line to a song or piece of literature) but hard to guess (people who know you should not be able to guess the passphrase). Remember this passphrase as you cannot re-import an encrypted volume without it. In other words, if you forget the passphrase, the data on the volume can become inaccessible if you need to re-import the pool. Protect this passphrase as anyone who knows it could re-import your encrypted volume, thwarting the reason for encrypting the disks in the first place.

Once the passphrase is set, the name of this button will change to Change Passphrase. After setting or changing the passphrase, it is important to immediately create a new recovery key by clicking the Add recovery key button. This way, if the passphrase is forgotten, the associated recovery key can be used instead.

Download Key: click this icon to download a backup copy of the GELI encryption key. The encryption key is saved to the client system, not on the TrueNAS® system. You will be prompted to input the password used to access the TrueNAS® administrative GUI before the selecting the directory in which to store the key. Since the GELI encryption key is separate from the TrueNAS® configuration database, it is highly recommended to make a backup of the key. If the key is every lost or destroyed and there is no backup key, the data on the disks is inaccessible.

Encryption Re-key: generates a new GELI encryption key. Typically this is only performed when the administrator suspects that the current key may be compromised. This action also removes the current passphrase.

Note

A re-key is not allowed if Failovers (High Availability) has been enabled and the standby node is down.

Add recovery key: generates a new recovery key. This screen prompts for entry of the password used to access the TrueNAS® administrative GUI and then to select the directory in which to save the key. Note that the recovery key is saved to the client system, not on the TrueNAS® system. This recovery key can be used if the passphrase is forgotten. Always immediately add a recovery key whenever the passphrase is changed.

Remove recover key: Typically this is only performed when the administrator suspects that the current recovery key may be compromised. Immediately create a new passphrase and recovery key.

Note

The passphrase, recovery key, and encryption key must be protected. Do not reveal the passphrase to others. On the system containing the downloaded keys, take care that the system and its backups are protected. Anyone who has the keys has the ability to re-import the disks if they are discarded or stolen.

Warning

If a re-key fails on a multi-disk system, an alert is generated. Do not ignore this alert as doing so may result in the loss of data.

7.1.10. View Multipaths¶

TrueNAS® uses gmultipath(8) to provide multipath I/O support on systems containing hardware that is capable of multipath. An example would be a dual SAS expander backplane in the chassis or an external JBOD.

Multipath hardware adds fault tolerance to a NAS as the data is still available even if one disk I/O path has a failure.

TrueNAS® automatically detects active/active and active/passive multipath-capable hardware. Any multipath-capable devices that are detected will be placed in multipath units with the parent devices hidden. The configuration will be displayed in Storage → Volumes → View Multipaths. Note that this option is not be displayed in the Storage → Volumes tree on systems that do not contain multipath-capable hardware.

7.1.11. Replacing a Failed Drive¶

Replace failed drives as soon as possible to repair the degraded state of the RAID.

Before physically removing the failed device, go to Storage → Volumes → View Volumes. Select the volume’s name. At the bottom of the interface are several icons, one of which is Volume Status. Click the Volume Status icon and locate the failed disk. Then perform these steps:

1. Click the disk’s entry, then its Offline button to change that disk’s status to OFFLINE. This step is needed to properly remove the device from the ZFS pool and to prevent swap issues. Click the disk’s Offline button and pull the disk. If there is no Offline button but only a Replace button, the disk is already offlined and you can safely skip this step.

   Note

   If the process of changing the disk’s status to OFFLINE fails with a “disk offline failed - no valid replicas” message, the ZFS volume must be scrubbed first with the Scrub Volume button in Storage → Volumes → View Volumes. After the scrub completes, try to Offline the disk again before proceeding.

2. After the disk has been replaced and is showing as OFFLINE, click the disk again and then click its Replace button. Select the replacement disk from the drop-down menu and click the Replace Disk button. After clicking the Replace Disk button, the ZFS pool starts to resilver and the status of the resilver is displayed.

3. After the drive replacement process is complete, re-add the replaced disk in the S.M.A.R.T. Tests screen.

In the example shown in Figure 7.1.17, a failed disk is being replaced by disk ada5 in the volume named volume1.

Fig. 7.1.17 Replacing a Failed Disk

After the resilver is complete, Volume Status shows a Completed resilver status and indicates any errors. Figure 7.1.18 indicates that the disk replacement was successful in this example.

Fig. 7.1.18 Disk Replacement is Complete

7.1.12. Replacing Drives to Grow a ZFS Pool¶

The recommended method for expanding the size of a ZFS pool is to pre-plan the number of disks in a vdev and to stripe additional vdevs using Volume Manager as additional capacity is needed.

However, this is not an option if you do not have open drive ports or the ability to add a SAS/SATA HBA card. In this case, you can replace one disk at a time with a larger disk, wait for the resilvering process to incorporate the new disk into the pool completes, then repeat with another disk until all of the disks have been replaced.

The safest way to perform this is to use a spare drive port or an eSATA port and a hard drive dock. In this case, you can perform the following steps:

1. Shut down the system.
2. Install one new disk.
3. Start up the system.
4. Go to Storage → Volumes, select the pool to expand and click the Volume Status button. Select a disk and click the Replace button. Choose the new disk as the replacement.
5. The status of the resilver process can be viewed by running zpool status. When the new disk has resilvered, the old one will be automatically offlined. The system can then be shut down to physically remove the replaced disk. One advantage of this approach is that there is no loss of redundancy during the resilver.

If you do not have a spare drive port, you will need to replace one drive with a larger drive using the instructions in Replacing a Failed Drive. This process is slow and places the :system in a degraded state. Since a failure at this point could be disastrous, do not attempt this method unless the system has a reliable backup. Replace one drive at a time and wait for the resilver process to complete on the replaced drive before replacing the next drive. Once all the drives are replaced and the resilver completes, you will see the added space in the pool.

7.3.1. Configure PULL¶

A copy of the public key for the replication user on PUSH needs to be pasted to the public key of the replication user on the PULL system.

To obtain a copy of the replication key: on PUSH go to Storage → Replication Tasks → View Replication Tasks. Click the View Public Key button and copy its contents. An example is shown in Figure 7.3.1.

Fig. 7.3.1 Copy the Replication Key

Go to PULL and click Account → Users → View Users. Click the Modify User button for the user account you will be using for replication (by default this is the root user). Paste the copied key into the SSH Public Key field and click OK. If a key already exists, append the new text after the existing key.

On PULL, ensure that the SSH service is enabled in Services → Control Services. Start it if it is not already running.

7.3.2. Configure PUSH¶

On PUSH, verify that a periodic snapshot task has been created and that at least one snapshot is listed in Storage → Snapshots.

To create the replication task, click Storage → Replication Tasks → Add Replication which opens the screen shown in Figure 7.3.2. For this example, the required configuration is as follows:

• the Volume/Dataset is local/data
• the Remote ZFS Volume/Dataset is remote
• the Remote hostname is 192.168.2.6
• the Begin and End times are at their default values, meaning that replication will occur whenever a snapshot is created
• once the Remote hostname is input, click the SSH Key Scan button; if the address is reachable and the SSH service is running on PULL, its key will automatically be populated to the Remote hostkey box

Fig. 7.3.2 Adding a Replication Task

Table 7.3.1 summarizes the available options in the Add Replication screen.

By default, replication occurs when snapshots occur. For example, if snapshots are scheduled for every 2 hours, replication occurs every 2 hours. The initial replication can take a significant period of time, from many hours to possibly days, as the structure of the entire ZFS pool needs to be recreated on the remote system. The actual time will depend upon the size of the pool and the speed of the network. Subsequent replications will take far less time, as only the modified data will be replicated.

The Begin and End times can be used to create a window of time where replication occurs. The default times allow replication to occur at any time of the day a snapshot occurs. Change these times if snapshot tasks are scheduled during office hours but the replication itself should occur after office hours. For the End time, consider how long replication will take so that it finishes before the next day’s office hours begin.

After the replication task is saved, PUSH will immediately attempt to replicate its latest snapshot to PULL. If the replication is successful, the snapshot appears in the Storage → Snapshots tab of PULL. Also, the Last snapshot sent to remote side and Status fields of Storage → Snapshots on PUSH indicate when the last snapshot was successfully sent to that Remote Hostname. If the snapshot is not replicated, refer to Troubleshooting Replication for troubleshooting tips.

7.3.3. Troubleshooting Replication¶

If you have followed all of the steps above and PUSH snapshots are not replicating to PULL, check to see if SSH is working properly. On PUSH, open Shell and try to ssh into PULL. Replace hostname_or_ip with the value for PULL:

ssh -vv -i /data/ssh/replication hostname_or_ip

This command should not ask for a password. If it asks for a password, SSH authentication is not working. Go to Storage → Replication Tasks and click the View Public Key button. Make sure that it matches one of the values in /~/.ssh/authorized_keys on PULL, where ~ represents the home directory of the replication user.

Also check /var/log/auth.log on PULL and /var/log/messages on PUSH to see if either log gives an indication of the error.

If the key is correct and replication is still not working, try deleting all snapshots on PULL except for the most recent one. In Storage → Snapshots check the box next to every snapshot except for the last one (the one with 3 icons instead of 2), then click the global Destroy button at the bottom of the screen.

Once you have only one snapshot, open Shell on PUSH and use the zfs send command. To continue our example, the ZFS snapshot on the local/data dataset of PUSH is named auto-20110922.1753-2h, the IP address of PULL is 192.168.2.6, and the ZFS volume on PULL is remote. Note that the @ is used to separate the volume/dataset name from the snapshot name:

zfs send local/data@auto-20110922.1753-2h | ssh -i /data/ssh/replication 192.168.2.6 zfs receive local/data@auto-20110922.1753-2h

After successfully transmitting the snapshot, check again after the time period between snapshots lapses to see if the next snapshot successfully transmitted. If it is still not working, you can manually send the specified snapshot with this command:

zfs send local/data@auto-20110922.1753-2h | ssh -i /data/ssh/replication 192.168.2.6 zfs receive local/data@auto-20110922.1753-2h