SSD TRIM for LUKS encrypted LVM partitions in Slackware

Tonus · 03-09-2022, 04:48 AM

Hi all

I followed the Slackware way (README_CRYPT.TXT and README_LVM.TXT) for my laptop.

Since 15.0 arrival, I did a fresh install and set up decryption at boot for old lvm/crypt disk and since these 2 disks are SSD, I wanted to have your advice on a few questions :

Should I neglect the 'security breach enabling TRIM on encrypted volume ?
Shall I bother with TRIM ?
Is the mkinitrd.conf option LUKSTRIM enough ?
How do I properly set TRIM for LUKS on LVM ?

Thanks for your enlightments !

BigTig · 03-09-2022, 11:41 PM

I've been using lvm on luks for my laptops for a few years and the LUKSTRIM option in the mkinitrd has been fine.
I just add a cron job to run fstrim weekly and that's about it.

Tonus · 03-10-2022, 02:55 PM

Thank you for your input !

Could you share the cron job you use ?

BigTig · 03-10-2022, 03:12 PM

Sure!

I just put the fstrim command in a short shell script that I place in the /etc/cron.weekly directory.

Code:

 #!/bin/bash
LOG=/var/log/TrimFS.log
DATE=$(date +%m-%d-%Y-%I:%M%p)

echo "----------$DATE--------" |tee -a $LOG
fstrim -a -v | tee -a $LOG
echo "------------------------------------" | tee -a $LOG

I like to keep a log of stuff for troubleshooting purposes, so you could just use the fstrim command and be done with it.

Tonus · 03-10-2022, 04:14 PM

Adapted and tested :-)
Perfect, thanks !