Table of Contents
Enable SSD Trim automatically
Continues TRIM
The real reason Ubuntu doesn’t TRIM SSDs by default is because the Linux kernel’s implementation of TRIM is slow and results in poor performance in normal use. Windows sends a TRIM command each time it deletes a file, telling the drive to immediately delete the bits of the file. Linux supports this when file systems are mounted with the “discard” option. However, Debian, Ubuntu — and other distributions — don’t do this by default for performance reasons. Continuous TRIM is not the most preferred way to issue TRIM commands in Linux. Continuous TRIM is enabled by the discard option for a mount in /etc/fstab: enables continuous TRIM in device operations:
/dev/sda1 / ext4 defaults,discard 0 1
Periodic trim
Copy the available templates to the systemctl directory and enable and start them.
# cp /usr/lib/systemd/system/fstrim.{service,timer} /etc/systemd/system
# systemctl enable fstrim.timer
# systemctl start fstrim.timer
In case these templates are not available, see the contents below:
# cat fstrim.service [Unit] Description=Discard unused blocks on filesystems from /etc/fstab Documentation=man:fstrim(8) [Service] Type=oneshot ExecStart=/sbin/fstrim -Av
# cat fstrim.timer [Unit] Description=Discard unused blocks once a week Documentation=man:fstrim [Timer] OnCalendar=weekly AccuracySec=1h Persistent=true [Install] WantedBy=timers.target
Check the status of the .timer with:
# systemctl list-timers
The output is quite useful:
EXT LEFT LAST PASSED UNIT ACTIVATES Sun 2017-12-10 00:11:06 CET 6h left Sat 2017-12-09 14:48:34 CET 2h 56min ago apt-daily.timer apt-daily.service Sun 2017-12-10 06:11:27 CET 12h left Sat 2017-12-09 06:47:46 CET 10h ago apt-daily-upgrade.timer apt-daily-upgrade.servi Sun 2017-12-10 16:28:34 CET 22h left Sat 2017-12-09 16:28:34 CET 1h 16min ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean. Mon 2017-12-11 00:00:00 CET 1 day 6h left n/a n/a fstrim.timer fstrim.service