Date: Mon, 9 Nov 1998 16:56:12 +1030 From: Greg Lehey <grog@lemis.com> To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: "Kenneth D. Merry" <ken@plutotech.com>, bill@bilver.magicnet.net, freebsd-fs@FreeBSD.ORG Subject: RAID-3 and RAID-4 (was: RAID1 Software vs Hardware) Message-ID: <19981109165612.K499@freebie.lemis.com> In-Reply-To: <199811090624.XAA25317@pluto.plutotech.com>; from Justin T. Gibbs on Sun, Nov 08, 1998 at 11:17:36PM -0700 References: <19981109142601.F499@freebie.lemis.com> <199811090624.XAA25317@pluto.plutotech.com>
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On Sunday, 8 November 1998 at 23:17:36 -0700, Justin T. Gibbs wrote: >> On Sunday, 8 November 1998 at 0:17:36 -0700, Justin T. Gibbs wrote: >>>>> RAID 3 is still used, and is still useful. All of Pluto's products (see >>>>> http://www.plutotech.com) use RAID 3. It works quite well for video data. >>>> >>>> I suppose it gives you good throughput. But how do you handle the I/O >>>> load? Are you effectively delivering a single video stream? >>> >>> RAID 3 is ideal when your data requests are always a multiple of the strip >>> size. >> >> I'm not sure we're talking about the same thing. In my book, RAID-3 >> is a RAID-4 with a stripe size of 1 byte. How do you define it? > > RAID-3 confines parity to 1 member of the array. The size of the stripe > is not a part of the specification. In the case of Pluto products, we > usually use a stripe size of 1MB which implies a per-unit access of > 1MB/N-1 (N being number of members in the RAID group). This looks like RAID-4 to me. Where do you see the difference? Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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