Date: Mon, 20 Mar 2000 15:23:31 -0600 From: Dan Nelson <dnelson@emsphone.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Alfred Perlstein <bright@wintelcom.net>, Matthew Dillon <dillon@apollo.backplane.com>, current@FreeBSD.ORG Subject: Re: patches for test / review Message-ID: <20000320152330.A48212@dan.emsphone.com> In-Reply-To: <20211.953581241@critter.freebsd.dk>; from "Poul-Henning Kamp" on Mon Mar 20 20:40:41 GMT 2000 References: <20000320115902.C14789@fw.wintelcom.net> <20211.953581241@critter.freebsd.dk>
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In the last episode (Mar 20), Poul-Henning Kamp said: > In message <20000320115902.C14789@fw.wintelcom.net>, Alfred Perlstein writes: > >* Poul-Henning Kamp <phk@critter.freebsd.dk> [000320 11:45] wrote: > >> > >> Before we redesign the clustering, I would like to know if we > >> actually have any recent benchmarks which prove that clustering is > >> overall beneficial ? > > > >Yes it is really benificial. > > I would like to see some numbers if you have them. For hardware RAID arrays that support it, if you can get the system to issue writes that are larger than the entire RAID-5 stripe size, your immensely slow "read parity/recalc parity/write parity/write data" operations turn into "recalc parity for entire stripe/write entire stripe". RAID-5 magically achieves RAID-0 write speeds! Given 32k granularity, and 8 disks per RAID group, you'll need a write size of 32*7 = 224k. Given 64K granularity and 27 disks, that's 1.6MB. I have seen the jump in write throughput as I tuned an Oracle database's parameters on both Solaris and DEC Unix boxes. Get Oracle to write blocks larger than a RAID-5 stripe, and it flies. -- Dan Nelson dnelson@emsphone.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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