Date: Wed, 23 Dec 2009 12:20:23 -0800 From: "David P. Discher" <dpd@bitgravity.com> To: Alexander Zagrebin <alexz@visp.ru> Cc: 'Attilio Rao' <attilio@freebsd.org>, freebsd-current@freebsd.org Subject: Re: 8.0-RELEASE: disk IO temporarily hangs up (ZFS or ATA related problem) Message-ID: <DEF95B1B-DBF9-4DC7-BEFF-4D8518D23601@bitgravity.com> In-Reply-To: <FECE64D8325144AD8E65DF1F1D1B0D35@vosz.local> References: <39309F560B98453EBB9AEA0F29D9D80E@vosz.local> <3bbf2fe10912181004w2a1abff2re8f77fd6a8bc3233@mail.gmail.com> <FECE64D8325144AD8E65DF1F1D1B0D35@vosz.local>
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ZFS will write buffer ALOT. Your settings of vfs.zfs.arc_min and = vfs.zfs.arc_max will likely affect how bursty this is. I've been = running with Min, 32 GB arc, and see very bursty writes (of course, my = systems have 64GB).=20 Also, use 'zpool iostat 1' and not the system iostat. Check gstat as = well. also try using CAM_ATA (ahci.ko) instead of ad devices, so your can get = the benefits of tag queuing. There is also a possible undocumented issue with, I believe it was the = WD green drives, where the vibration of the drive actually slowed it = down. This was demonstrated by setting a pound or two of silly putty on = the top of the drive, and its performance (significantly) increased. = Experiment with putting some heavily, non-conductive weight on top of = each drive - a book or something. ensure that is its securely mounted = as well.=20 --- David P. Discher dpd@bitgravity.com * AIM: bgDavidDPD BITGRAVITY * http://www.bitgravity.com On Dec 18, 2009, at 12:04 PM, Alexander Zagrebin wrote: >>> The disks are used for mirrored ZFS pool. >>> I have noticed that the system periodically locks up on=20 >> disk operations. >>> After approx. 10 min of very slow disk i/o (several KB/s)=20 >> the speed of disk >>> operations restores to normal. >>> gstat has shown that the problem is in ad6. >>=20 >> Want you try this patch and report?: >> http://people.freebsd.org/~attilio/lockmgr_lostwake.diff >>=20 >> It should apply to STABLE_8 and if not, just report and I will help. >=20 > Thanks fo your attempt to help! > I've successfully applied this patch to RELENG_8_0, recompiled > kernel and required modules (krpc, opensolaris,zfs), > but nothing has changed. The problem still exist. >=20 > --=20 > Alexander Zagrebin >=20 > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to = "freebsd-current-unsubscribe@freebsd.org"
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