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Date: Fri, 31 Oct 2008 15:44:19 +1100
From: Andrew Snow <andrew@modulus.org>
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To: Jeremy Chadwick <koitsu@FreeBSD.org>
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Cc: freebsd-fs@freebsd.org, Danny Carroll <fbsd@dannysplace.net>
Subject: Re: Areca vs. ZFS performance testing.
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Jeremy Chadwick wrote:
> I would recommend you stick with a consistent set of loader.conf
> tuning variables, and focus entirely on comparing the performance of
> ZFS on the Areca controller vs. the ICH controller.

Its probably worth playing with vfs.zfs.cache_flush_disable when using 
the hardware RAID.

By default, ZFS will flush the entire hardware cache just to make sure 
the ZFS Intent Log (ZIL) has been written.

This isn't so bad on a group of hard disks with small caches, but bad if 
you have 256mb of controller write cache.