Date: Mon, 31 Jan 2000 07:32:31 -0700 (MST) From: "Justin T. Gibbs" <gibbs@narnia.plutotech.com> To: Greg Lehey <grog@lemis.com> Cc: scsi@FreeBSD.org Subject: Re: hardware vs software stripping Message-ID: <200001311432.HAA32638@narnia.plutotech.com> In-Reply-To: <Pine.BSF.4.10.10001301401360.60037-100000@server.b0x.com> <20000131104827.A62824@freebie.lemis.com>
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In article <20000131104827.A62824@freebie.lemis.com> you wrote: > > I suppose you mean striping. RAID-5 doesn't stripe at the byte level, > it stripes at the block level. RAID-3 stripes at the byte level. I've heard you say this several times, but it is simply not true. RAID-3 is the same as RAID4 without the optimization for partial stripe writes. In otherwords, in RAID-3, you must read or write a full stripe where RAID-4 adds the ability to perform RMW operations on the parity block of the stripe for sub-stripe updates. Pluto uses a RAID-3 system in its video server products and it is certainly not striped on a byte level. (Just as an aside, given the minimum 512 byte sector size of most magnetic media, striping an a per byte basis would be really wasteful). -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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