8.0-RELEASE: disk IO temporarily hangs up (ZFS or ATA
Johan at double-l.nl
Mon Dec 28 08:21:31 UTC 2009
>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).
>Also, use 'zpool iostat 1' and not the system iostat. Check gstat as
>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.
Even with hardware the FreeBSD Handbook comes Handy ;-)
> ensure that is its securely mounted as well.
>David P. Discher
>dpd at 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
>>> disk operations.
>>>> After approx. 10 min of very slow disk i/o (several KB/s)
>>> the speed of disk
>>>> operations restores to normal.
>>>> gstat has shown that the problem is in ad6.
>>> Want you try this patch and report?:
>>> It should apply to STABLE_8 and if not, just report and I will help.
>> 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.
>> Alexander Zagrebin
>> freebsd-current at freebsd.org mailing list
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