TrueNAS SCALETrueNAS SCALE Nightly Development Documentation
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Managing S.M.A.R.T. Tests

S.M.A.R.T. or Self-Monitoring, Analysis and Reporting Technology is a standard for disk monitoring and testing. You can monitor disks for problems using different kinds of self-tests. TrueNAS can adjust when it issues S.M.A.R.T. alerts. When S.M.A.R.T. monitoring reports a disk issue, we recommend you replace that disk. Most modern ATA, IDE, and SCSI-3 hard drives support S.M.A.R.T. Refer to your respective drive documentation for confirmation.

TrueNAS runs S.M.A.R.T. tests on disks. Running tests can reduce drive performance, so we recommend scheduling tests when the system is in a low-usage state. Avoid scheduling disk-intensive tests at the same time! For example, do not schedule S.M.A.R.T. tests on the same day as a disk scrub or other data protection task.

How do I check or change S.M.A.R.T. testing for a disk?

Go to Storage, then click Disks button. Select disks to be examined using the checkbox at left. Click the to the right of the disk row to expand it. Enable S.M.A.R.T. shows as true or false.

To enable or disable testing, click EDIT and find the Enable S.M.A.R.T. option.

Running a Manual S.M.A.R.T. Test

To test one or more disk for errors, go to Storage and click the Disks button.


Select the disks you want to test using the checkboxes to the left of the disk names. Selecting multiple disks displays the Batch Operations options.


Click Manual Test. The Manual S.M.A.R.T. Test dialog displays.

Manual S.M.A.R.T. tests on NVMe devices is currently not supported.


Next, select the test type from the Type dropdown and then click Start.

Test types differ based on the drive connection, ATA or SCSI. Test duration varies based on the test type you chose. TrueNAS generates alerts when tests discover issues.

ATA Drive Connection Test Types

The ATA drive connection test type options are:

  • Long runs a S.M.A.R.T. Extended Self Test that scans the entire disk surface, which may take hours on large-volume disks.
  • Short runs a basic S.M.A.R.T. Short Self Test (usually under ten minutes) that varies by manufacturer.
  • Conveyance runs a S.M.A.R.T. Conveyance Self Test (usually only minutes) that identifies damage incurred while transporting the device.
  • Offline runs a S.M.A.R.T. Immediate Offline Test that updates the S.M.A.R.T. Attribute values. Errors will appear in the S.M.A.R.T. error log.

SCSI Drive Connection Test Type

  • Long runs the “Background long” self-test.
  • Short runs the “Background short” self-test.
  • Offline runs the default self-test in the foreground, but doesn’t place an entry in the self-test log.

For more information, refer to smartctl(8).

Where can I view the test results? Click the in a disk’s row to expand it, then click S.M.A.R.T. TEST RESULTS. You can also see results in the Shell using smartctl and the name of the drive: smartctl -l selftest /dev/ada0.

Running Automatic S.M.A.R.T. Tests

To schedule recurring S.M.A.R.T. tests, go to Data Protection and click ADD in the S.M.A.R.T. Tests widget.


Select the disks to test from the Disks dropdown list, and then select the test type to run from the Type dropdown list.

Next select a preset from the Schedule dropdown. To create a custom schedule select Custom to open the advanced scheduler window where you can define the schedule parameters you want to use.

Advanced Scheduler


Choosing a Presets option populates in the rest of the fields. To customize a schedule, enter crontab values for the Minutes/Hours/Days.

These fields accept standard cron values. The simplest option is to enter a single number in the field. The task runs when the time value matches that number. For example, entering 10 means that the job runs when the time is ten minutes past the hour.

An asterisk (*) means match all values.

You can set specific time ranges by entering hyphenated number values. For example, entering 30-35 in the Minutes field sets the task to run at minutes 30, 31, 32, 33, 34, and 35.

You can also enter lists of values. Enter individual values separated by a comma (,). For example, entering 1,14 in the Hours field means the task runs at 1:00 AM (0100) and 2:00 PM (1400).

A slash (/) designates a step value. For example, entering * in Days runs the task every day of the month. Entering */2 runs it every other day.

Combining the above examples creates a schedule running a task each minute from 1:30-1:35 AM and 2:30-2:35 PM every other day.

TrueNAS has an option to select which Months the task runs. Leaving each month unset is the same as selecting every month.

The Days of Week schedules the task to run on specific days in addition to any listed days. For example, entering 1 in Days and setting Wed for Days of Week creates a schedule that starts a task on the first day of the month and every Wednesday of the month.

The Schedule Preview displays when the current settings mean the task runs.

Examples of CRON syntax

*Every item.* (minutes) = every minute of the hour.
* (days) = every day.
*/NEvery Nth item.*/15 (minutes) = every 15th minute of the hour.
*/3 (days) = every 3rd day.
*/3 (months) = every 3rd month.
Comma and hyphen/dashEach stated item (comma)
Each item in a range (hyphen/dash).
1,31 (minutes) = on the 1st and 31st minute of the hour.
1-3,31 (minutes) = on the 1st to 3rd minutes inclusive, and the 31st minute, of the hour.
mon-fri (days) = every Monday to Friday inclusive (every weekday).
mar,jun,sep,dec (months) = every March, June, September, December.

You can specify days of the month or days of the week.

TrueNAS lets users create flexible schedules using the available options. The table below has some examples:

Desired scheduleValues to enter
3 times a day (at midnight, 08:00 and 16:00)months=*; days=*; hours=0/8 or 0,8,16; minutes=0
(Meaning: every day of every month, when hours=0/8/16 and minutes=0)
Every Monday/Wednesday/Friday, at 8.30 pmmonths=*; days=mon,wed,fri; hours=20; minutes=30
1st and 15th day of the month, during October to June, at 00:01 ammonths=oct-dec,jan-jun; days=1,15; hours=0; minutes=1
Every 15 minutes during the working week, which is 8am - 7pm (08:00 - 19:00) Monday to FridayNote that this requires two tasks to achieve:
(1) months=*; days=mon-fri; hours=8-18; minutes=*/15
(2) months=*; days=mon-fri; hours=19; minutes=0
We need the second scheduled item, to execute at 19:00, otherwise we would stop at 18:45. Another workaround would be to stop at 18:45 or 19:45 rather than 19:00.


Saved schedules appear in the S.M.A.R.T. Tests window.

S.M.A.R.T. tests can offline disks! Avoid scheduling S.M.A.R.T. tests simultaneously with scrub or other data protection tasks.

Start the S.M.A.R.T. service. Go to System > Services and scroll down to the S.M.A.R.T. service. If not running, click the toggle to turn the service on. Select Start Automatically to have this service start after after the system reboots.


If you have not configured the S.M.A.R.T. service yet, while the service is stopped, click to open the service configuration form. See Services S.M.A.R.T. Screen for more information on service settings. Click Save to save settings and return to the Services screen.

RAID controllers? Disable the S.M.A.R.T. service when a RAID controller controls the disks. The controller monitors S.M.A.R.T. separately and marks disks as a Predictive Failure on a test failure.

Using Shell to View Scheduled Tests

CLI To verify the schedule is saved, you can open the shell and enter smartd -q showtests.