Date: Wed, 5 Sep 2001 14:40:34 -0700 From: "Chad R. Larson" <chad@DCFinc.com> To: David Gilbert <dgilbert@velocet.ca> Cc: Doug Hardie <bc979@lafn.org>, Lawrence Farr <l.farr@epcdirect.co.uk>, "'Greg Lehey'" <grog@FreeBSD.ORG>, "'Lawrence Farr'" <lawrence@epcdirect.co.uk>, "'Chris BeHanna'" <behanna@zbzoom.net>, "'FreeBSD-Stable'" <stable@FreeBSD.ORG> Subject: Re: [stable] Re: RAID5 Message-ID: <20010905144034.C6345@freeway.dcfinc.com> In-Reply-To: <15254.16593.350305.548246@trooper.velocet.net>; from dgilbert@velocet.ca on Wed, Sep 05, 2001 at 11:12:17AM -0400 References: <002c01c135e4$69c924d0$c80aa8c0@lfarr> <f04330116b7bbe195e610@[10.0.1.100]> <15254.16593.350305.548246@trooper.velocet.net>
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On Wed, Sep 05, 2001 at 11:12:17AM -0400, David Gilbert wrote: > Now imagine the softupdates case: If the RAID-5 information was > managed by softupdates (or similar system), we could identify multiple > updates to blocks in the same RAID group at the filesystem level and > avoid as many as 6 of the 14 writes. Moreover, this might actually be > managed at the buffer-cache level instead of the current system where > the blocks are forced out to disk synchronously. Large commercial disk farms such as the EMC Symetrics or the Sun A3500 do something like that. They have ECC memory with it's own battery back up, and the reads and writes are to that memory. The hard drives are basically backing store for the RAM. -crl -- Chad R. Larson (CRL15) 602-953-1392 Brother, can you paradigm? chad@dcfinc.com chad@larsons.org larson1@home.com DCF, Inc. - 14623 North 49th Place, Scottsdale, Arizona 85254-2207 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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