Date: Wed, 21 Apr 2004 15:02:10 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Jens Schweikhardt <schweikh@schweikhardt.net> Cc: freebsd-scsi@freebsd.org Subject: Re: Hardware Striping Message-ID: <20040421210209.GA34084@panzer.kdm.org> In-Reply-To: <20040421204409.GA44407@schweikhardt.net> References: <20040421204409.GA44407@schweikhardt.net>
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On Wed, Apr 21, 2004 at 22:44:09 +0200, Jens Schweikhardt wrote: > hello, world\n > > I want to change my system to no longer use vinum for striping, but > rather a hardware solution. I do not intend to use mirroring or any > other RAIDn>0 functionality. I have two pairs of identical U160 SCSI > disks (2 Fujitsu MAN and MAM with 36GB each) where I want to build two > mirrors, one from the MANs, and one from the MAMs. You get the idea. > > Until now I'm using an Adaptec 29160 Host Adapter, but of course it is > not HW-RAID0 capable. What card am I looking for? The only reason to go with a hardware controller for RAID-0 is if you want to boot from the array. Otherwise, you'll get better performance by using a software RAID-0 solution. Going through a RAID stack and a SCSI layer on a RAID card with a comparatively slow processor will generally be slower than using your much faster host processor to do all of that. ccd is an alternative if you don't want to use vinum. > The disks have a sustained read rate of 60 to 70 Mbyte/s, so if all of > them were used at the same time they could saturate an U160 bus. Is this > a problem? It's not a problem, unless you're interested in performance. I'd suggest a 2 channel Ultra160 or Ultra320 RAID controller. Hopefully the processor on the RAID controller will be able to keep up with the 280MB/sec theoretical maximum bandwidth from those disks. As for alternatives, you could get an Adaptec 2200S, or an LSI MegaRAID SCSI 320-2. I think the driver for the Adaptec is probably a little better maintained at the moment. I haven't used either card, though, so I can't really comment on them more than to point out the alternatives. Ken -- Kenneth Merry ken@kdm.org
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