Date: Fri, 26 Oct 2001 17:54:14 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Greg Lehey <grog@FreeBSD.org> Cc: Doug Rabson <dfr@nlsystems.com>, Luigi Rizzo <rizzo@aciri.org>, John Baldwin <jhb@FreeBSD.org>, Jonathan Lemon <jlemon@FreeBSD.org>, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: Re: RAID-5 parity calculations (was: cvs commit: src/sys/dev/fxp if_fx) Message-ID: <Pine.BSF.4.21.0110261753401.12956-100000@beppo> In-Reply-To: <20011027102214.C7091@wantadilla.lemis.com>
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Sorry, that seems wrong to me. Typical RAID write performance for something like an Sun A1000 which has a pentium in it is about 50% of theoretical. On Sat, 27 Oct 2001, Greg Lehey wrote: > On Thursday, 25 October 2001 at 15:24:06 -0700, Matt Jacob wrote: > > > > And the fastest software RAID-V I've known was at NASA/Ames on the > > Convex 3280s- they used the otherwise unused vector units for parity > > calculations- this gave write performance for a 22 wide stripe on a > > terabyte fileystem to be at about 88% of theoretical maximum, which > > sure aint' bad. > > The parity calculations for RAID-5 are several orders of magnitude > faster than the disk accesses. Even on a 486, they took hardly any > time. > > Greg > -- > See complete headers for address and phone numbers > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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