Wie gesagt - was hat man zu verlieren? Man hat mehr Sicherheit für den Fall der Fälle, auch wenn man jetzt noch nicht absehen kann, wie ein solcher Fall aussehen würde.
Bezüglich Trim kopiere ich einfach mal eine Anleitung rein. Habe ich selbst noch nicht umgesetzt und weiß daher nicht, ob das aktuell nicht sogar schon in Distros integriert ist.
- Make a backup of all your data. You're messing with your file system so having a backup is simply a good idea.
- Make sure you have the required kernel and cryptsetup versions (3.1 & 1.4, e.g. in Ubuntu 12.04, beware though, at time of writing 12.04 is still beta).
- Add discard parameter to the file system options of the encrypted LVM volume(s) in your /etc/fstab file. This makes the file system of your LVM partition aware that you want to use TRIM.
- The last step is not enough though. As long as LUKS is not aware that you want to use TRIM it will effectively block all TRIM operations coming from the LVM partition's file system, for security reasons. Add discard parameter to the cryptdevice options in /etc/crypttab to make LUKS accept the discard behavior of the LVM partition.
- Rebuild your initramfs. The crypttab options are stored there and used on boot.
- Reboot.
- Check if TRIM is now active.
- If the last command shows a result like this (1 allow_discards at the end) you're all set.