On Tue, 17 Sep 2013, Jorge Fábregas wrote: > Date: Tue, 17 Sep 2013 14:38:08 -0400 > From: Jorge Fábregas <jorge.fabregas@gmail.com> > Reply-To: LVM general discussion and development <linux-lvm@redhat.com> > To: linux-lvm@redhat.com > Subject: LVM & fstrim behaviour (Fedora 19) > > Hi, > > I'm testing fstrim on an LVM volume but it only seems to work the first > time I run it (just after mounting the volume). When I run "fstrim -v > /mnt" for the first time it prints all the free blocks that is trimming > (almost all of the filesystem as it is empty) but subsequent runs just > output "0 bytes trimmed" no matter how many files I create/sync & delete > afterwards. The "issue_discards" is set in lvm.conf. > > If I do this over the raw device (/dev/sda3, same ext4 filesystem) I get > the output corresponding to the last deleted files every time I run fstrim. > > ## THIN ## > > I also created a thin pool and a logical volume on that pool. If I > mount this volume with "discard", I can see that TRIM is working by > doing an "lvs vgthin" (the Data Usage% grows as I create files & shrinks > as I delete files). However, If I mount it without the "discard" option > (in order to use fstrim) I only see the data-usage reduction when I run > fstrim *just* for the first time. > > Any help will be appreciated. Can you blktrace output for the devivce you're doing the fstrim on ? Both when you run fstrim for the first time and then when you run it again after releasing some blocks from the file system. blktrace -d /dev/sda -o - | blkparse -i - viz. man blktrace Can you share how many a what size are the files you're releasing before running fstrim again ? Are you using sync after removing those files and before running fstrim (that's pretty important since blocks are not released instantly from the ext4 file system - but you can force it with sync). I can confirm that fstrim on ext4 works as expected with loop image and I do not see behaviour described by Jorge. I'll try thinp as well to see what's going on. Thanks! -Lukas > > Thanks, > Jorge > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ >
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