Date: Mon, 17 Nov 2008 13:15:41 +1000 From: Danny Carroll <fbsd@dannysplace.net> To: =?ISO-8859-1?Q?Eirik_=D8verby?= <ltning@anduin.net> Cc: freebsd-fs@freebsd.org, freebsd-hardware@freebsd.org Subject: Re: Areca vs. ZFS performance testing. Message-ID: <4920E1DD.7000101@dannysplace.net> In-Reply-To: <CEDCDD3E-B908-44BF-9D00-7B73B3C15878@anduin.net> References: <490A782F.9060406@dannysplace.net> <20081031033208.GA21220@icarus.home.lan> <490A849C.7030009@dannysplace.net> <20081031043412.GA22289@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>
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Eirik Øverby wrote: > I have noticed that my 3ware controllers, after updating firmware > recently, have removed the JBOD option entirely, classifying it as > something you wouldn't want to do with that kind of hardware anyway. I > believed then, and even more so now, they are correct. It kinda depends. If there were a good 8 or 16+ port SATA card out there that *simply* did SATA with no bells and whistles, then there would be no point buying a Raid adaptor when you want to use things like ZFS. But there are no such cards available. > Use the RAID-0 disk trick to be able to utilize the controller cache. > And regarding write-back vs write-through; I believe write-through is > equvivalent to disabling controller write cache, however it WILL cache > the writes in order to respond to future reads of the data being > written. I would guess, but I don't know, that this also goes for > disk-level caches too, though, so it probably doesn't matter. It is interesting to me that the default setting on the Areca card was to have the disk caches turned on. I think that is strange because by default you have a situation that can lead to data loss even if you have a battery backup unit. -D
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