Date: Thu, 8 Jan 2009 08:48:33 +0100 From: "Koen Smits" <kgysmits@gmail.com> To: fbsd@dannysplace.net Cc: freebsd-fs@freebsd.org, Jeremy Chadwick <koitsu@freebsd.org>, freebsd-hardware@freebsd.org Subject: Re: Areca vs. ZFS performance testing. Message-ID: <b072dc420901072348n7d094937u89b6d24959f8ae3d@mail.gmail.com> In-Reply-To: <496549D9.7010003@dannysplace.net> References: <20081031033208.GA21220@icarus.home.lan> <490A8FAD.8060009@dannysplace.net> <491BBF38.9010908@dannysplace.net> <491C5AA7.1030004@samsco.org> <491C9535.3030504@dannysplace.net> <CEDCDD3E-B908-44BF-9D00-7B73B3C15878@anduin.net> <4920E1DD.7000101@dannysplace.net> <F55CD13C-8117-4D34-9C35-618D28F9F2DE@spry.com> <20081117070818.GA22231@icarus.home.lan> <496549D9.7010003@dannysplace.net>
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> One thing I am at a loss to understand is why turning off the disk > caches when testing the JBOD performance produced almost identical (very > slightly better) results. Perhaps it was a case of the ZFS internal > cache making the disks cache redundant? Comparing to the ARECA > passthrough (where the areca cache is used) shows again, similar results. > > -D > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" My guess is it probably has to do with the way ZFS does cache flushes: http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Cache_Flushes It might be worth it to disable the forced flushing and test again, if you feel like it. -Koen
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