Hello! I have some questions about the TRIM/discard for LUKS-encrypted SSDs. I currently have a custom Ubuntu 20.04 LTS setup with encrypted ext4 rootfs partition (it's /dev/sda2 and /dev/sda1 is the EFI partition) on an HDD that I'd like to migrate to an SSD. I was originally going to do a block-for-block copy using dd, but I figured it'd be better and faster to copy just the files from rootfs and the EFI partition rather than the entire disk. So I'm going to setup a new LUKS volume (same parameters) on the SSD and then sync the filesystem contents over there. This got me thinking about optimizing the system for SSD since it was originally installed on an HDD. While googling for information I found out about two types of TRIM: continuous and periodic. The docs say that the continuous mode is activated by adding a "discard" parameter to the rootfs mount options in /etc/fstab or by activating a certain flag by tune2fs. The periodic mode is activated by placing the fstrim utility on a timer i.e. a weekly cron job or systemd timer. I noticed the latter is already active on my system. Anyway, I was wondering how this is handled when dm-crypt lies between the SSD and the filesystem. Do I need to take any additional steps in this case or will fstrim do its thing as is? I'm just checking because there is so much contradicting information available online. Some people mentioned that a "discard" parameter should be added to /etc/crypttab entry, others claim they must be present on both files - fstab and crypttab. Some even suggest to add an "allow-discards" parameter to the GRUB kernel command line in /etc/default/grub file. I was also told that the continuous TRIM is discouraged and that periodic should be used instead. What's the correct thing to do here? Thanks in advance. _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx https://www.saout.de/mailman/listinfo/dm-crypt
