From owner-cvs-all Sun Aug 8 0:13:32 1999 Delivered-To: cvs-all@freebsd.org Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (Postfix) with ESMTP id 7D60714C38; Sun, 8 Aug 1999 00:13:15 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id QAA25209; Sun, 8 Aug 1999 16:40:26 +0930 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id QAA22214; Sun, 8 Aug 1999 16:40:25 +0930 (CST) Date: Sun, 8 Aug 1999 16:40:24 +0930 From: Greg Lehey To: Andreas Klemm Cc: John-Mark Gurney , cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/vinum vinuminterrupt.c Message-ID: <19990808164024.E10056@freebie.lemis.com> References: <199908070806.BAA66984@freefall.freebsd.org> <19990807181938.49481@hydrogen.fircrest.net> <19990808105939.A10056@freebie.lemis.com> <19990808085758.A2467@titan.klemm.gtn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.4i In-Reply-To: <19990808085758.A2467@titan.klemm.gtn.com>; from Andreas Klemm on Sun, Aug 08, 1999 at 08:57:59AM +0200 WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk On Sunday, 8 August 1999 at 8:57:59 +0200, Andreas Klemm wrote: > On Sun, Aug 08, 1999 at 10:59:39AM +0930, Greg Lehey wrote: >> On Saturday, 7 August 1999 at 18:19:38 -0700, John-Mark Gurney wrote: >>> Greg Lehey scribbled this message on Aug 7: >>>> Import RAID-5 code. >>>> 1.12 +224 -3 src/sys/dev/vinum/vinuminterrupt.c >>> >>> so, does this mean that you can use RAID-5 w/o having to buy anything? >> >> Yes. > > How fast would RAID5 be with a AHA2940 and 3 IBM DORS disks connected to > it (5400U/Min, 5.4 MB/sec using bonnie). Is it still fast, 50% of speed ... That depends on what you're doing. bonnie doesn't really tell you very much; you need to measure the raw throughput. Also, it depends on what kind of load you're putting on it. Do you intend to have multiple processes accessing the volume at the same time? What's your read/write ratio? RAID-5 is slow on writes, but fast enough on reads. Having said that, 3 drives isn't very much for RAID-5. You use a third of the space for parity, and you don't get the read performance benefits that you'd get with more drives. To measure both conventional drives and Vinum volumes, use rawio (ftp://ftp.lemis.com/pub/rawio.tar.gz). > I know difficult to say ... but only want to know, if it's a doable > compromise instead of doing hardware RAID... There's currently no reason to believe that hardware RAID will give you better performance until you start to max out the CPU, which appears unlikely. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message