Date: Thu, 23 Mar 2000 15:27:18 -0800 From: Greg Lehey <grog@lemis.com> To: Dan Nelson <dnelson@emsphone.com> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, Alfred Perlstein <bright@wintelcom.net>, Matthew Dillon <dillon@apollo.backplane.com>, current@FreeBSD.ORG Subject: Re: patches for test / review Message-ID: <20000323152718.C9318@mojave.worldwide.lemis.com> In-Reply-To: <20000320152330.A48212@dan.emsphone.com>; from dnelson@emsphone.com on Mon, Mar 20, 2000 at 03:23:31PM -0600 References: <20000320115902.C14789@fw.wintelcom.net> <20211.953581241@critter.freebsd.dk> <20000320152330.A48212@dan.emsphone.com>
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On Monday, 20 March 2000 at 15:23:31 -0600, Dan Nelson wrote: > 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. Agreed. This is on the Vinum wishlist, but it comes at the expense of reliability (how long do you wait to cluster? What happens if the system fails in between?). In addition, for Vinum it needs to be done before entering the hardware driver. 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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