Howdy, I have seen a number of folks run into issues due to ZFS file system fragmentation, and was curious if anyone on team ZFS is working on this issue? Would it be possible to share with the list any changes that will be made to to help address fragmentation problems? Thanks, - Ryan -- UNIX Administrator http://prefetch.net
Not sure is it related to the fragmentation, but I can say that serious performance degradation in my NFS/ZFS benchmarks [1] is a result of on-disk ZFS data layout. Read operations on directories (NFS3 readdirplus) are abnormally time consuming . That kills the server. After cold restart of the host the performans is still on the flour. My conclusion: it''s not CPU, not memory, it''s ZFS on-disk structures. [1] http://www.opensolaris.org/jive/thread.jspa?threadID=24014 This message posted from opensolaris.org
Matty wrote:> Howdy, > > I have seen a number of folks run into issues due to ZFS file system > fragmentation, and was curious if anyone on team ZFS is working on > this issue? Would it be possible to share with the list any changes > that will be made to to help address fragmentation problems?We have some ideas, one of which is to periodically do an on-line "defrag" by relocating most of the blocks. This is obviously not the most elegant solution, but it may work. We''re currently investigating... --matt
Any progress on a defragmentation utility? We appear to be having a severe fragmentation problem on an X4500, vanilla S10U4, no additional patches. 500GB disks in 4 x 11 disk RAIDZ2 vdevs. It hit 97% full and fell off a cliff...about 50KB/sec on writes. Deleting files so the zpool is at 92% has not helped. I rebooted the host...no difference. I lowered the recordsize from 128KB to 8KB. That has boosted performance to 250-500KB/sec on writes (still 10x-100x too slow). Reads have been fine all along. This is one big zpool and one file system of 16TB. Approximately 25-30M files, some of which change often. Lots of small, changing files, which are probably aggravating the problem. Due to the Marvell driver bug, I have SATA NCQ turned off in /etc/system via "set sata:sata_func_enable=0x5". We plan to go to the most recent patch set so I can remove that, but I''m not convinced patching will fix the slowness we''re seeing. We''ll try to delete more files, but having a defragmentation utility might help in this case. It seems a shame to waste 10-20% of your disk space to maintain moderate performance, though I guess that''s what we''ll have to do. This message posted from opensolaris.org
Lance, This could be bug#*6596237 Stop looking and start ganging <http://monaco.sfbay/detail.jsf?cr=6596237>.* The fix is in progress and Victor Latushkin is working on it. We have an IDR based on the patches 127127-11/127128-11 which has the first cut of the fix. You could raise an escalation and get these IDRs. Thanks and regards, Sanjeev. Lance wrote:> Any progress on a defragmentation utility? We appear to be having a severe fragmentation problem on an X4500, vanilla S10U4, no additional patches. 500GB disks in 4 x 11 disk RAIDZ2 vdevs. It hit 97% full and fell off a cliff...about 50KB/sec on writes. Deleting files so the zpool is at 92% has not helped. I rebooted the host...no difference. I lowered the recordsize from 128KB to 8KB. That has boosted performance to 250-500KB/sec on writes (still 10x-100x too slow). Reads have been fine all along. > > This is one big zpool and one file system of 16TB. Approximately 25-30M files, some of which change often. Lots of small, changing files, which are probably aggravating the problem. Due to the Marvell driver bug, I have SATA NCQ turned off in /etc/system via "set sata:sata_func_enable=0x5". We plan to go to the most recent patch set so I can remove that, but I''m not convinced patching will fix the slowness we''re seeing. > > We''ll try to delete more files, but having a defragmentation utility might help in this case. It seems a shame to waste 10-20% of your disk space to maintain moderate performance, though I guess that''s what we''ll have to do. > > > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >-- Solaris Revenue Products Engineering, India Engineering Center, Sun Microsystems India Pvt Ltd. Tel: x27521 +91 80 669 27521