[SOLVED] How often should I use use fstrim?

nigelc · 05-24-2018, 05:17 AM

My first drive is an ssd drive which contains the system + /var etc. Not much other data ever gets put there so I hardy ever run fstrim.

The question is How often should I run fstrim?

Code:

 df shows this

df
Filesystem Size Used Avail Use% Mounted on
devtmpfs 12G 0 12G 0% /dev
tmpfs 12G 3.1M 12G 1% /dev/shm
tmpfs 12G 1.1M 12G 1% /run
/dev/sda1 102G 7.5G 89G 8% /
tmpfs 12G 0 12G 0% /sys/fs/cgroup
tmpfs 12G 4.0K 12G 1% /tmp
/dev/sdb1 1.8T 480G 1.3T 28% /home
tmpfs 2.4G 0 2.4G 0% /run/user/983
tmpfs 2.4G 44K 2.4G 1% /run/user/500
[nigel@localhost ~]

[/code]

syg00 · 05-24-2018, 06:21 AM

Did you consider that the manpage might be a good place to start ?.

AwesomeMachine · 05-26-2018, 01:13 AM

fstrim runs automatically on most ditros.

wpeckham · 05-26-2018, 07:28 AM

What format is your file system and is it mounted using the "discard" option?

This is not distribution specific, but file system specific.

If you are using a file system that understands SSD and has the "discard" option then it does "trim" dynamically and automagicly as blocks are allocated and deallocated. For those file systems you might never need fstrim, but running it once per week or month will not hurt.

If your file system does not understand and detect SSD, and does not mount with "discard", then you might want to run fstrim on a schedule, but how often will depend upon your priorities and usage patterns.

So, how have you formatted your file systems?

BW-userx · 05-26-2018, 08:34 AM

Quote:

Originally Posted by AwesomeMachine

fstrim runs automatically on most ditros.

does it not require an entry in fstab to tell it where to run each time it boots up? I put a script in my cron.weekly to gett'er done.

nigelc · 05-27-2018, 06:22 AM

Hello,

Quote:

What format is your file system and is it mounted using the "discard" option

The drive is formatted as an ex4 file system and is not mounted using the discard option.
mount says:

Code:

/dev/sda1 on / type ext4 (rw,relatime,data=ordered)

Cheers Nigel

wpeckham · 05-27-2018, 09:47 AM

Quote:

Originally Posted by nigelc

Hello,

The drive is formatted as an ex4 file system and is not mounted using the discard option.
mount says:

Code:

/dev/sda1 on / type ext4 (rw,relatime,data=ordered)

Cheers Nigel

EXT4 is a great file system, but it does not autodetect SSD and does not add "discard" by default. You can change the mouont to include that option, as it is supported in the newer ext4 drivers. Check your man pages for detail.

If you do NOT add the option, or if it is not supported at your level, then run fstrim either on boot or a safe schedule for your usage profile. (Your usage profile is based upon how often files change allocations on your disk. The more often you change the disk allocation the more often you should trim the fs. )

NOT adding the discard option is valid, as dynamic trim can impact performance. If you need the maximum I/O speed from the SSD, do not enable discard on mount, but do run fstrim.

Note that there is not much advantage in doing trim on only one level. Someone using crypt, lvm, and ext4 would have to enable trim at three different levels to resolve all of the allocation repair. If you keep things simple life is easier, and this is very doable.

See interesting discussion here http://blog.neutrino.es/2013/howto-p...m-and-dmcrypt/ and here https://sites.google.com/site/easylinuxtipsproject/ssd

Using a file system (btrfs for example) that has SSD autodetection and handling might work for you.

ondoho · 05-28-2018, 12:14 AM

thanks for the info; i had a look at the "easylinuxtips" link, but then also had a look at my native https://wiki.archlinux.org/index.php/SSD - it had this to say about discard:

Quote:

Warning: Unfortunately, there are wide quality gaps of SSD's bios' to perform continuous TRIM, which is also why using the discard mount flag is recommended against generally by ext filesystem developer Theodore Ts'o. If in doubt about your hardware, apply #Periodic TRIM instead.

since i bought the cheapest SSD available, i did that:

Quote:

The util-linux package provides fstrim.service and fstrim.timer systemd unit files. Enabling the timer will activate the service weekly.

the arch wiki does not mention noatime, but i think i'll try it at least.

nigelc · 05-28-2018, 12:30 AM

Thanks for the info:
It seems to be there in systemctl, but not enabled.

Code:

 systemctl status fstrim.timer
● fstrim.timer - Discard unused blocks once a week
   Loaded: loaded (/usr/lib/systemd/system/fstrim.timer; enabled; vendor preset:
   Active: inactive (dead)
     Docs: man:fstrim

Half an hour later

The question is How I enable it?

I may have got it now. I think it runs on Monday morning.

Code:

 systemctl start fstrim.timer
[root@localhost ~]# systemctl status fstrim.timer
● fstrim.timer - Discard unused blocks once a week    {The dot thing is now green}
   Loaded: loaded (/usr/lib/systemd/system/fstrim.timer; enabled; vendor preset:
   Active: active (waiting) since Mon 2018-05-28 15:38:51 AEST; 6s ago
     Docs: man:fstrim

cheers.

ondoho · 05-28-2018, 01:26 AM

you also need to enable it (otherwise it won't restart upon systemd restart, reboot that is):

Code:

systemctl enable fstrim.timer

BW-userx · 05-28-2018, 06:00 AM

here is a web page that explains trim and discard, and shows how to set up either one of them.

http://www.webupd8.org/2013/01/enabl...te-drives.html

(I posted this somewhere, I thought it was in here, now I wonder which thread it is in)

AwesomeMachine · 05-29-2018, 01:58 AM

Quote:

Originally Posted by BW-userx

does it not require an entry in fstab to tell it where to run each time it boots up? I put a script in my cron.weekly to gett'er done.

Ideally, I guess it's best to check before assuming.

BW-userx · 05-29-2018, 06:58 AM

Quote:

Originally Posted by AwesomeMachine

Ideally, I guess it's best to check before assuming.

to run trim at boot up : fstab : on a time schedule cron : or command line using a calendar to keep track of time past. forming a question eliminates the assumption and puts the burden on the second party. And from what @ondoho posted it looks like their is even another option now out there that I did not know about, as I don't systemD (much).

systemctl enable fstrim.timer

nigelc · 06-06-2018, 02:52 AM

Hi,
I think it has worked now..

Code:

 ~]# journalctl -u fstrim
-- Logs begin at Sun 2018-01-14 16:00:11 AEDT, end at Wed 2018-06-06 17:35:28 AEST. --
Jun 04 11:01:49 localhost.localdomain systemd[1]: Starting Discard unused blocks...
Jun 04 11:01:51 localhost.localdomain systemd[1]: Started Discard unused blocks.

Thanks for the help