Solid State Drives

Post installation, you will need to enable TRIM for solid state drives. You can check which devices allow TRIM by running:

$ lsblk --discard

If the DISC-GRAN (discard granularity) and DISC-MAX (discard maximum bytes) columns are non-zero, that means the block device has TRIM support. If your solid state drive partition does not show TRIM support, please verify that you chose a file system with TRIM support (ext4, Btrfs, F2FS, etc.). Note that F2FS requires kernel 4.19 or above to support TRIM.

To run TRIM one-shot, you can run fstrim(8) manually. For example, if your / directory is on an SSD:

# fstrim /

To automate running TRIM, use cron or add the discard option to /etc/fstab.

Periodic TRIM with cron

Add the following lines to /etc/cron.weekly/fstrim:


fstrim /

Finally, make the script executable:

# chmod u+x /etc/cron.weekly/fstrim

Continuous TRIM with fstab discard

You can use either continuous or periodic TRIM, but usage of continuous TRIM is discouraged if you have an SSD that doesn't handle NCQ correctly. Refer to the kernel blacklist.

Edit /etc/fstab and add the discard option to block devices that need TRIM.

For example, if /dev/sda1 was an SSD partition, formatted as ext4, and mounted at /:

/dev/sda1  /           ext4  defaults,discard   0  1


To enable TRIM for LVM's commands (lvremove, lvreduce, etc.), open /etc/lvm/lvm.conf, uncomment the issue_discards option, and set it to 1:



Warning: Before enabling discard for your LUKS partition, please be aware of the security implications.

To open an encrypted LUKS device and allow discards to pass through, open the device with the --allow-discards option:

# cryptsetup luksOpen --allow-discards /dev/sdaX luks

Non-root devices

Edit /etc/crypttab and set the discard option for devices on the SSD. For example, if you have a LUKS device with the name externaldrive1, device /dev/sdb2, and password none:

externaldrive1  /dev/sdb2   none    luks,discard

Root devices

If your root device is on LUKS, add rd.luks.allow-discards to CMDLINE_LINUX_DEFAULT. In the case of GRUB, edit /etc/default/grub:


Then update GRUB:

# update-grub

Verifying configuration

To verify that you have configured TRIM correctly for LUKS, reboot and run:

# dmsetup table /dev/mapper/crypt_dev --showkeys

If this command output contains the string allow_discards, you have successfully enabled TRIM on your LUKS device.


Before running trim on a ZFS pool, ensure that all devices in the pool support it:

# zpool get all | grep trim

If the pool allows autotrim (set off by default), you can trim the pool periodically or automatically. To one-shot trim yourpoolname:

# zpool trim yourpoolname

Periodic TRIM

Add the following lines to /etc/cron.daily/ztrim:

zpool trim yourpoolname

Finally, make the script executable:

# chmod u+x /etc/cron.daily/ztrim


To set autotrim for yourpoolname, run:

# zpool set autotrim=on yourpoolname