On Tue, 24 Sep 2013, Lukáš Czerner wrote: > Date: Tue, 24 Sep 2013 15:20:13 +0200 (CEST) > From: Lukáš Czerner <lczerner@redhat.com> > Reply-To: LVM general discussion and development <linux-lvm@redhat.com> > To: Jorge Fábregas <jorge.fabregas@gmail.com> > Cc: linux-lvm@redhat.com > Subject: Re: LVM & fstrim behaviour (Fedora 19) > > 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. I've tried it with thinp targer and it works as expected: # mkfs.ext4 /dev/lvm_pool/thin_lv # mount /dev/lvm_pool/thin_lv /mnt/test # dd if=/dev/zero of=/mnt/test/file bs=1M count=1024 # dd if=/dev/zero of=/mnt/test/file1 bs=1M count=1024 # dd if=/dev/zero of=/mnt/test/file2 bs=1M count=1024 # sync # lvs pool lvm_pool twi-a-tz- 9,00g 35,83 thin_lv lvm_pool Vwi-aotz- 50,00g pool 6,45 # rm -f /mnt/test/file # sync # fstrim -v /mnt/test /mnt/test: 47 GiB (50508640256 bytes) trimmed # lvs pool lvm_pool twi-a-tz- 9.00g 33.54 thin_lv lvm_pool Vwi-aotz- 50.00g pool 6.04 # rm -f /mnt/test/file* # sync # fstrim -v /mnt/test /mnt/test: 47 GiB (50508640256 bajtů) trimmed # lvs pool lvm_pool twi-a-tz- 9.00g 16.44 thin_lv lvm_pool Vwi-aotz- 50.00g pool 2.96 # lvm version LVM version: 2.02.98(2) (2012-10-15) Library version: 1.02.77 (2012-10-15) Driver version: 4.24.0 -Lukas > > 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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