wiki.ubuntuusers.de says if I want to use TRIM on an encrypted SSD, I need at least cryptsetup 1.4 and kernel 3.1. Do I need this, when creating the partitions and setting up encryption, or is upgrading afterwards enough?
Ubuntu 11.10 Oneiric does not ship with cryptsetup 1.4, although Precise does. I don't know whether cryptsetup can be upgraded on Oneiric or not. Since Precise will be released in a month, you can also wait for that release before considering TRIM with encrypted partitions. The kernel can always be upgraded afterwards.
As you can see, this feature is not enabled by default because of the degraded security as mentioned in the linked blog. So, if you use cryptsetup on kernel 3.0 (the one shipped with Precise), you won't have TRIM support on your encrypted partitions. After upgrading to 3.1+, you still don't have unless you enable it.
To do so, you have to edit
I have posted a step by step guide to enabling TRIM with LUKS encrypted partitions in Ubuntu 12.04 or any Debian with cryptsetup 1.4+ and Kernel 3.1+. (Feel free to copy it here if some askubuntu guidelines deem it necessary.)
Find the Howto here: