On Sat, Jan 07, 2012 at 02:02:02PM +1100, Chris Samuel wrote:
On Sat, 7 Jan 2012, 13:28:41 EST, Craig Sanders <cas@taz.net.au> wrote:
Does anyone use fstrim on an XFS formatted SSD partition?
I've got two systems with XFS root partitions that fstrim seems to do (almost) nothing on, but it seems to work correctly on another system with formatted with ext4.
This was discussed on the btrfs list recently for the same reason (ext4 vs btrfs behaviour).
URL?
The FS does send the trims to the device in both cases but ext4 remembers what's been trimmed whilst that fs is mounted. It's not recorded in the the ext4 fs though so if you remount it'll trim again.
OK, that sounds like it's some sort of optimisation in ext4 so that subsequent fstrim runs are faster. I'm still not sure why fstrim says (on the 2nd and subsequent runs on XFS) that it has trimmed almost the same amount of data. what is it actually counting here? bytes in data blocks that (might) need trimming? byte-counts in TRIM commands sent to the device? something else? something still seems screwy, or at least counter-intuitive. craig -- craig sanders <cas@taz.net.au> BOFH excuse #243: The computer fleetly, mouse and all.