Date: Tue, 18 Sep 2007 18:21:47 -0300 From: Joao Carlos Mendes Luis <jonny@jonny.eng.br> To: Ashley Moran <work@ashleymoran.me.uk> Cc: hardware@freebsd.org Subject: Re: SATA mirrror performance Message-ID: <46F0416B.4010607@jonny.eng.br> In-Reply-To: <CC565B45-9D16-4FBE-BB54-6AC5A09AC973@ashleymoran.me.uk> References: <46EDDDD0.2070409@jonny.eng.br> <CC565B45-9D16-4FBE-BB54-6AC5A09AC973@ashleymoran.me.uk>
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Ashley Moran wrote: > > On Sep 17, 2007, at 2:52 am, João Carlos Mendes Luís wrote: > >> After using gmirror, now I have the RAID in its full performance, >> getting over 60Mbytes per second at raw reads, very near the 70MBps from >> the specs. Could only be better if we already had NCQ working. >> >> Now the question: Is this expected? Is ataraid somehow deprecated? > > I had no end of trouble with ataraid. At first I was under the > impression it was the best solution, seeing as it has some support > from the motherboard. But after posting to a list (possibly > -hardware) a long time ago, all the answers I got were to use > gmirror. I don't know that ataraid is deprecated, but I can't think > of any reason to use it. Fortunately (as you have found), turning an > ataraid mirror into a gmirror is easy. I would just use gmirror and > not worry about it. The main advantage of ataraid is its integration with BIOS and other operating systems. If we had something like a master GEOM device which could read ata raid specs and build GEOM graphs based on this information, that would be a good workaround. I am not sure if this is enough, but at least would solve startup problems. I am also not sure if it is even possible, because no single GEOM device would suffice: The master device should recognize disk labels, and call geom_mirror, geom_strip, geom_raid5, etc when needed. I hope GEOM architects have something in mind, because this is very important to desktop and dual boot. I can deal with geom_mirror, but I am not a typical user. Most users don't even know FreeBSD supports mirroring, since it is not on installation options menu. Indeed, install a FreeBSD with boot mirror support was still a complex task the last time I saw sysinstall. Thanks for your info, anyway...
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