Date: Thu, 19 Aug 2004 08:33:58 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: "Greg 'groggy' Lehey" <grog@FreeBSD.org> Cc: Wilko Bulte <wb@freebie.xs4all.nl> Subject: Re: RAID-3? Message-ID: <11555.1092897238@critter.freebsd.dk> In-Reply-To: Your message of "Thu, 19 Aug 2004 15:52:28 %2B0930." <20040819062228.GO85432@wantadilla.lemis.com>
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In message <20040819062228.GO85432@wantadilla.lemis.com>, "Greg 'groggy' Lehey" writes: >On Thursday, 19 August 2004 at 0:00:55 -0600, Scott Long wrote: >> >> I think that you're really reading far too much into this. > >That depends on whether you care about accurate terminology or not. >Or maybe it's you who is reading too much into the matter. I think being accurate is a great thing, but accuracy of definition should never get in the way of working code. The main features of RAID3 are the always full stripe access which keeps your disk heads running in tandem which has desirable performance characteristica. Also the fact that you can trivially add ECC instead of mere parity is a big plus. Raid5 with two bit ECC (sometimes called raid6) is a royal nightmare to code (see the raidframe paper) whereas RAID3 in 4+2 or 8+3 is pretty trivial because of the full-stripe access pattern. Now, can we stop the definition-thumbing and let Pawel work on his code ? If need be, put this on your bumper-sticker: If you don't like RAID3 then don't use it! Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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