Date: Wed, 4 Mar 1998 19:05:12 +0100 (MET) From: Wilko Bulte <wilko@yedi.iaf.nl> To: shimon@simon-shapiro.org Cc: karl@mcs.net, sbabkin@dcn.att.com, tlambert@primenet.com, jdn@acp.qiv.com, blkirk@float.eli.net, hackers@FreeBSD.ORG, grog@lemis.com Subject: Re: SCSI Bus redundancy... Message-ID: <199803041805.TAA01136@yedi.iaf.nl> In-Reply-To: <XFMail.980303222332.shimon@simon-shapiro.org> from Simon Shapiro at "Mar 3, 98 10:23:32 pm"
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As Simon Shapiro wrote... > > On 04-Mar-98 Karl Denninger wrote: > > ... > > > The best I've seen off our RAID systems right now is about 11MB/sec > > (that's > > megaBYTES, not bits). That's on an Ultra bus, with 2 ultra busses going > > to > > the RAID disks. > > About right. SCSI-II used to be 4-5 MB/bus. Ultra-wide is about 5-6, for > small O/S-type blocks. I see about 18 MB/Sec on the DPT on three busses. > The difficulty is in having FreeBSD capable of producing this traffic on > small blocks (dd if=/dev/zero of=/dev/something bs=64k is NOT typical > application). Build a datawarehouse and do full-table reads etc. For dataprocessing etc you will never come near. We've seen host adapters becoming saturated before the RAIDbox. This is of course using an artificial benchmark that produces 100% cache hits on the RAIDbox' cache. > > I could run two host channels on this thing across two RAID sets into two > > Adaptec adapters. That might be a big win. That could be possible, highly depends on the adapter & driver. But for single stream a well written driver & good card will probably not be the bottleneck. Wilko _ ______________________________________________________________________ | / o / / _ Bulte email: wilko @ yedi.iaf.nl http://www.tcja.nl/~wilko |/|/ / / /( (_) Arnhem, The Netherlands - Do, or do not. There is no 'try' --------------- Support your local daemons: run [Free,Net,Open]BSD Unix -- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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