Date: Tue, 26 Oct 1999 11:06:15 -0400 From: Greg Lehey <grog@lemis.com> To: Geoff Buckingham <geoffb@chuggalug.clues.com> Cc: Mike Tancsa <mike@sentex.net>, freebsd-current@freebsd.org Subject: Re: AMRD (MegaRAID) BIOS rev another other questions Message-ID: <19991026110615.51265@mojave.worldwide.lemis.com> In-Reply-To: <19991026112647.B95499@chuggalug.clues.com>; from Geoff Buckingham on Tue, Oct 26, 1999 at 11:26:47AM %2B0100 References: <3.0.5.32.19991020143339.016e0210@staff.sentex.ca> <19991022140949.A82396@chuggalug.clues.com> <19991024095811.61238@mojave.worldwide.lemis.com> <19991026112647.B95499@chuggalug.clues.com>
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On Tuesday, 26 October 1999 at 11:26:47 +0100, Geoff Buckingham wrote: > 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 There's a big difference between 768 kB and 767½ kB. That's the point I was trying to make. With 768 kB, you risk having all your superblocks on one drive. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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