[please don't top-post, please remove CC's, please trim quotes. it's really tedious to clean up your post to make it readable.]
Marc Nicholas <geekyth...@gmail.com> writes: > Brent Jones <br...@servuhome.net> wrote: >> Marc Nicholas <geekyth...@gmail.com> wrote: >>> Kjetil Torgrim Homme <kjeti...@linpro.no> wrote: >>>> his problem is "lazy" ZFS, notice how it gathers up data for 15 >>>> seconds before flushing the data to disk. tweaking the flush >>>> interval down might help. >>> >>> How does lowering the flush interval help? If he can't ingress data >>> fast enough, faster flushing is a Bad Thibg(tm). if network traffic is blocked during the flush, you can experience back-off on both the TCP and iSCSI level. >>>> what are the other values? ie., number of ops and actual amount of >>>> data read/written. this remained unanswered. >> ZIL performance issues? Is writecache enabled on the LUNs? > This is a Windows box, not a DB that flushes every write. have you checked if the iSCSI traffic is synchronous or not? I don't use Windows, but other reports on the list have indicated that at least the NTFS format operation *is* synchronous. use zilstats to see. > The drives are capable of over 2000 IOPS (albeit with high latency as > its NCQ that gets you there) which would mean, even with sync flushes, > 8-9MB/sec. 2000 IOPS is the aggregate, but the disks are set up as *one* RAID-Z2! NCQ doesn't help much, since the write operations issued by ZFS are already ordered correctly. the OP may also want to try tweaking metaslab_df_free_pct, this helped linear write performance on our Linux clients a lot: http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6869229 -- Kjetil T. Homme Redpill Linpro AS - Changing the game _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
