Date: Tue, 26 Oct 1999 11:26:47 +0100 From: Geoff Buckingham <geoffb@chuggalug.clues.com> To: Greg Lehey <grog@lemis.com> Cc: Mike Tancsa <mike@sentex.net>, freebsd-current@FreeBSD.ORG Subject: Re: AMRD (MegaRAID) BIOS rev another other questions Message-ID: <19991026112647.B95499@chuggalug.clues.com> In-Reply-To: <19991024095811.61238@mojave.worldwide.lemis.com>; from Greg Lehey on Sun, Oct 24, 1999 at 09:58:11AM -0600 References: <3.0.5.32.19991020143339.016e0210@staff.sentex.ca> <19991022140949.A82396@chuggalug.clues.com> <19991024095811.61238@mojave.worldwide.lemis.com>
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On Sun, Oct 24, 1999 at 09:58:11AM -0600, Greg Lehey wrote: > > Indeed. It's quite easy to put all cylinder groups on a single > spindle; I've seen reports of up to 80% degradation under these > circumstances. > > > Where sequential read/write performance is not critical you can stripe at > > cluster size to avoid this. Other wise using an odd number of spindles for > > a stripe and an even number for a RAID3 or RAID5 or stripeing at an interval > > which is not a power of two should work (12,24,48,76 etc) > > The best I've heard of is 768 kB - 1 sector. This works on Vinum, but > it seems that most RAID controllers use a somewhat simplistic striping > algorithm. You might like to try 31 kB or such. This won't make any > difference with rawio, though. > I would agree from experiance that 768 KB seems a good selection for vinum and probably ccd too -- GeoffB To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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