Why is ssd trim disabled by default?

Feedback Feature Request
42

I don’t believe so, because since LVM v2 trim commands pass through the logical volumes by default. You can test this out yourself:

sudo fstrim -v -a

Wait for the command to finish. Any errors? Or does it output the results, such as:
/: 409.8 GiB (440062459904 bytes) trimmed on /dev/sda1

If all looks well, then the systemd timer and service will take care of the rest. The command you just manually invoked is essentially what fstrim.timer does on a weekly basis. Assuming the timer is active (see earlier in this thread). My above output is just an example, and I’m not using LVM, hence why you see /dev/sda1.

No need to change or add anything if it’s working as expected. :slight_smile:

1 Like
43

Yes, sudo fstrim -av reports no errors.

Thank you!

44

I permanently can activate the timer on my system with the command

systemctl enable --now fstrim.timer

So I don’t really see a problem…
But this didn’t happen automatically after the installation. Now I checked my installation log from summer 2020 to see what there was going on. Check it out for yourself:

…
Target cmd: (“systemctl”, “enable”, “fstrim.timer.service”) output:
Failed to enable unit, unit fstrim.timer.service does not exist.
2020-07-03 - 21:12:20 [2]: void CalamaresPython::warning(const string&)
WARNING:[PYTHON JOB]: “Cannot enable systemd .service fstrim.timer”
2020-07-03 - 21:12:20 [2]: void CalamaresPython::warning(const string&)
WARNING:[PYTHON JOB]: “systemctl enable call in chroot returned error code 1”
…

45

I reinstalled Manjaro Gnome today, and it was not enabled. I had to enable it using systemctl enable --now fstrim.timer

46

It appears the timer is not enabled by default.

That’s fine. Let the user decide. Besides, if you’re using encryption, you might want to understand the implications of using trim before enabling it.

47

The title: Why is ssd trim disabled by default?

The general answer for general defaults: Solid state drive - ArchWiki

Most SSDs support the ATA_TRIM command for sustained long-term performance and wear-leveling.
…
Warning: Users need to be certain that their SSD supports TRIM before attempting to use it. Data loss can occur otherwise!

48

$ man cryptsetup

--allow-discards
              Allow  the  use of discard (TRIM) requests for the device.  This option is only relevant for open action.  This is also not supported for LUKS2 devices with data integrity
              protection.

              WARNING: This command can have a negative security impact because it can make filesystem-level operations visible on the physical device. For example, information  leaking
              filesystem type, used space, etc. may be extractable from the physical device if the discarded blocks can be located later. If in doubt, do not use it.

              A kernel version of 3.1 or later is needed. For earlier kernels, this option is ignored.

Some person here says that “For most users, the benefit of TRIM outweigh those security concerns.” so while on my MJ the encryption is not set to use discard:

$ sudo fstrim -v /
fstrim: /: the discard operation is not supported

and system does not use fstrim:
$ systemctl status fstrim.timer

○ fstrim.timer - Discard unused blocks once a week
     Loaded: loaded (/usr/lib/systemd/system/fstrim.timer; disabled; vendor preset: disabled)
     Active: inactive (dead)

and my system encrypted drive seems to support TRIM (having non zero values DISC-GRAN & DISC-MAX):
$ lsblk --discard

NAME                                          DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
nvme0n1                                              0      512B       2T         0
├─nvme0n1p1                                          0      512B       2T         0
└─nvme0n1p2                                          0      512B       2T         0
  └─luks-a-b-c-d                                     0        0B       0B         0

i think i should use fstrim? But how to do it? The steps should be?

sudo nano /etc/crypttab
replace luks by luks,discard
(is it safe? i do not want non-bootable system)

Then:
$ systemctl enable --now fstrim.timer
?

49

I have one HDD and one SSD in my laptop. How should I enable the trimm feature only for the SSD?