Ubuntu – No SSD TRIM script in Ubuntu 20.04 LTS

20.04ssdtrim

I figured out that there is no fstrim script in /etc/cron.weekly. I've read that TRIM is automatically enabled for SAMSUNG SSD. I'm using Ubuntu 20.04 LTS and there is no fstrim script in all cron folders. In /etc/fstab discard isn't set either – but discard isn't recommended anyway.

I created now the fstrim script in /etc/cron.weekly. I hope that interferes with no other script or missed I something?

Best Answer

fstrim is managed by systemctl, not cron, and is defined by a systemd service unit called fstrim.service and a timer unit called fstrim.timer.

$ locate fstrim.service
...
/usr/lib/systemd/system/fstrim.service

Please use

$ systemctl status fstrim.timer

to check for the status of fstrim. It will show something like ...

● fstrim.timer - Discard unused blocks once a week
     Loaded: loaded (/lib/systemd/system/fstrim.timer; enabled; vendor preset: >
     Active: active (waiting) since Wed 2021-01-27 02:23:22 CET; 1 day 21h ago
    Trigger: Mon 2021-02-01 01:02:07 CET; 3 days left
   Triggers: ● fstrim.service
       Docs: man:fstrim

jan 27 02:23:22 discworld systemd[1]: Started Discard unused blocks once a week.

If that is not the same for you... the ssd might not be compatible.

Testing

One way you could test whether automatic trim is working would be to create and delete a large file:

user@host:/somewhere$ dd if=/dev/urandom bs=1M count=100 of=bigfile
user@host:/somewhere$ sync
user@host:/somewhere$ rm bigfile
user@host:/somewhere$ sync

If automatic discard is working, manually trimming again won't trim many blocks, since they should have already been trimmed. Run sudo discard -v on your filesystem and see how many blocks are trimmed.

Recommendation

As for which is recommended: In my experience, automatic trim kills performance. However, this is probably hardware-dependent; it may be fine on your drive.

If you're using manual trim, as for how often, think about the rate at which you write data in your typical workload, compared to the amount of free space on your SSD. You want to trim sufficiently often, before your disk fills up with deleted data. If your SSD is mostly free space or your disk workload is light, trimming occasionally (weekly or even longer) should suffice. If your SSD is mostly full or you e.g. edit video files frequently, you'll need to trim more often.

Ubuntu – Is SSD TRIM support still automatic in 12.10

TRIM support is built into Quantal 3.5 kernels but you need to enable it yourself using the discard mount option.

How to enable TRIM?

Best Answer

Related Solutions

Ubuntu – Automatic TRIM vs. manual TRIM

Testing

Recommendation

Ubuntu – Is SSD TRIM support still automatic in 12.10

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