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Boot Pool Management
6 minute read.
System > Boot contains options for monitoring and managing the ZFS pool and devices that store the TrueNAS operating system.
The Stats/Settings option displays current system statistics and provides the option to change the scrub interval, or how often the system runs a data integrity check on the operating system device.
Go to System > Boot screen and click Stats/Settings. The Stats/Settings window displays statistics for the operating system device: Boot pool Condition as ONLINE or OFFLINE, Size in GiB and the space in use in Used, and Last Scrub Run with the date and time of the scrub. By default, the operating system device is scrubbed every 7 days.
To change the default scrub interval, input a different number in Scrub interval (in days) and click Update Interval.
From the System > Boot screen, click the Boot Pool Status button to open the Boot Pool Status screen. This screen shows the boot-pool and expands to show the devices that are allocated to that pool. Read, write, or checksum errors are also shown for the pool.
A manual data integrity check (scrub) of the operating system device can be initiated at any time.
On the System > Boot screen, and click Scrub Boot Pool to open the Scrub dialog.
Click Confirm and then Start Scrub.
TrueNAS supports a ZFS feature known as boot environments. These are snapshot clones of the TrueNAS boot-pool install location that TrueNAS boots into. Only one boot environment is used for booting at a time.
A boot environment allows rebooting into a specific point in time and greatly simplifies recovering from system misconfigurations or other potential system failures. With multiple boot environments, the process of updating the operating system becomes a low-risk operation.
For example, the TrueNAS update process automatically creates a snapshot of the current boot environment and adds it to the boot menu before applying the update. If anything goes wrong during the update, the system administrator can activate the snapshot of the pre-update environment and reboot TrueNAS to restore system functionality.
Boot environments do not preserve or restore the state of any attached storage pools or apps, only the system boot-pool. Storage backups must be handled through the ZFS snapshot feature or other backup options. TrueNAS applications also use separate upgrade and container image management methods to provide app update and rollback features.
To view the list of boot environments on the system, go to System > Boot. Each boot environment entry contains this information:
- Name: the name of the boot entry as it appears in the boot menu.
- Active: indicates which entry boots by default if a boot environment is not active.
- Date Created: indicates the boot environment creation date and time.
- Space: shows boot environment size.
- Keep: indicates whether or not TrueNAS deletes this boot environment when a system update does not have enough space to proceed.
To access more options for a boot environment, click to display the list of options: