Here's some notes on how to setup stuff for trim. I hit this issue when my SSD / partition reported itself full with df -hT, but was actually only using 14 out of about 55 GiB.

I had followed some older how-to's that said add 'discard' to the partition mount in /etc/fstab, this is apparently not correct in general, so remove that first, then reboot to make sure the partition is mounted as expected.

Or do instead, along with removing the discard from /etc/fstab mount line:


Note that you can in fact remount / using the above command!

Read more about trim on the Arch Linux wiki: wiki.archlinux.org/index.php/Solid_state_drive#TRIM

To trim manually, do:

if you only have an SSD, that will trim all mounted partitions.

To trim only one, put the mount point, root in this case:


As you can see here, mounting / with discard never even worked as suggested, and was simply not the right thing to do, as damentz notes below.

For systemd users, you can enable systemd's scheduled trim with:


Damentz of Liquorix explained it this way:


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