From owner-cvs-all Fri Oct 26 20:51:12 2001 Delivered-To: cvs-all@freebsd.org Received: from wantadilla.lemis.com (wantadilla.lemis.com [192.109.197.80]) by hub.freebsd.org (Postfix) with ESMTP id 3BD7737B41E; Fri, 26 Oct 2001 20:49:41 -0700 (PDT) Received: by wantadilla.lemis.com (Postfix, from userid 1004) id 9E02C6ACC7; Sat, 27 Oct 2001 10:22:14 +0930 (CST) Date: Sat, 27 Oct 2001 10:22:14 +0930 From: Greg Lehey To: Matthew Jacob Cc: Doug Rabson , Luigi Rizzo , John Baldwin , Jonathan Lemon , cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: RAID-5 parity calculations (was: cvs commit: src/sys/dev/fxp if_fx) Message-ID: <20011027102214.C7091@wantadilla.lemis.com> References: <20011025231245.K549-100000@salmon.nlsystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from mjacob@feral.com on Thu, Oct 25, 2001 at 03:24:06PM -0700 Organization: The FreeBSD Project Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-418-838-708 WWW-Home-Page: http://www.FreeBSD.org/ X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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