On Feb 14, 2010, at 9:24 AM, Bogdan Ćulibrk wrote: > Greetings zfs-discuss@ > > I was trying to narrow this down for some quite time. The problem is resides > on couple of osol/sxce boxes that are used as dom0 hosts. Under high disk > load on domU guests (backup process for example) domU performance is > terrible. The worst thing is that iostat shows *very* high %w numbers, while > zpool iostat showing quite low numbers.
Where is iostat %w measured? > > Couple things that to mention: > 1. /etc/system tune: set zfs:zfs_arc_max = 524288000 > 2. dom0 is pinned to dedicated CPU, also memory is capped to 1GB. > 3. no hardware raid involved, raw SATA drives fed to dom0 under rpool. > 4. domUs are on top of zvols, 8K blocksize > 5. iostat: http://pastebin.com/m4bf1c409 Is this data from dom0? Looks like around 200-300 8KB random reads per second, which is about all you can expect from 3-5 SATA disks. -- richard > 6. zpool iostat: http://pastebin.com/m179269e2 > 7. domU definition: http://pastebin.com/m48f18a76 > 8. dom0 bits are snv_115, snv_124, snv_126 and snv_130 > 9. domUs have ext3 mounted with: noatime,commit=120 > 10. there are ~4 domUs per dom0 host, each having dedicated cpu(s). > > > Any hint would be apreciated where should I go from here. > > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
