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From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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To: Michael Gmelin <freebsd@grem.de>
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Cc: freebsd-fs@freebsd.org
Subject: Re: ZFS resilvering strangles IO
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On Tue, 8 May 2012, Michael Gmelin wrote:
>
> Do you think it would make sense to try to play with zfs_resilver_delay directly in the ZFS kernel module?

This may be the wrong approach if the issue is really that there are 
too many I/Os queued for the device.  Finding a tunable which reduces 
the maximum number of I/Os queued for a disk device may help reduce 
write latencies by limiting the backlog.

On my Solaris 10 system, I accomplished this via a tunable in 
/etc/system:
set zfs:zfs_vdev_max_pending = 5

What is the equivalent for FreeBSD?

Bob
-- 
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/