Hello! Please, may I ask you some questions because I'm a little bit confused about the behaviour of fstrim and online discard (ext4)? I'm using the following configuration / partitioning with a SSD (Controller: SF-2281; Corsair Force GT 240GB): - dm_crypt: cryptsetup luksOpen - version 1.4.1, device-mapper version 1.02.75 - lvm version 2.02.96 - ext4, option discard; kernel version 3.4.11 All seems to work fine, I can't see any errors in messages or in dmesg according trim / discard. Now, I tested fstrim from util-linux version 2.19, and surprisingly got this unexpected error: fstrim: /: FITRIM ioctl failed: Operation not supported Why do I get this error? Online discard always seemed to work fine (= I didn't get any error). I detected, that there is another necessary option to get a working fstrim: cryptsetup luksOpen must be run with option --allow-discards. Now my questions: - Did online discard work without --allow-discards? If not, why didn't I get any error message? - Is there a difference between online discard and fstrim, means, fstrim doesn't work without --allow-discards, but online discard does? - fstrim / always says after each reboot: /: 1701429248 bytes was trimmed This can't be true as the root partition contains mainly root and nothing else (no /var or /usr or even /opt). There has been no changes in fs since last power on / off cycle and fstrim during the last cycle. Doesn't fstrim remember the already trimmed regions? Does it trim always the complete unused regions? - Which trim should be used with a SF-2281 controller concerning endurance? fstrim or online discard? Thank you very much for your advice! Kind regards, Andreas -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
