From owner-freebsd-scsi Wed Feb 18 11:52:26 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA25900 for freebsd-scsi-outgoing; Wed, 18 Feb 1998 11:52:26 -0800 (PST) (envelope-from owner-freebsd-scsi@FreeBSD.ORG) Received: from sendero.simon-shapiro.org (sendero-fxp0.Simon-Shapiro.ORG [206.190.148.34]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id LAA25751 for ; Wed, 18 Feb 1998 11:51:38 -0800 (PST) (envelope-from shimon@sendero-fxp0.simon-shapiro.org) Received: (qmail 14451 invoked by uid 1000); 18 Feb 1998 19:30:23 -0000 Message-ID: X-Mailer: XFMail 1.3-alpha-020998 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <199802181850.TAA01578@yedi.iaf.nl> Date: Wed, 18 Feb 1998 11:30:23 -0800 (PST) Reply-To: shimon@simon-shapiro.org Organization: The Simon Shapiro Foundation From: Simon Shapiro To: Wilko Bulte Subject: Re: getting oriented with RAID Cc: freebsd-scsi@FreeBSD.ORG, curt@kcwc.com Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On 18-Feb-98 Wilko Bulte wrote: ... > You want to stay on the outside of your ZBR platters to achieve the > highest datarates. My age is showing ... :-) Yes, on modern disks, the number of sectors per platter varies, decreasing towards the spindle. >> Unless you want to do what I used to do for a living for many years >> (compute >> all this nonsense), just experiment with drives, busses, stripe sizes, >> amount of cache, cache utilization, host cache vs. DPT cache, etc. > > Not to forget write-back caching (with battery backup please) Of course. Caching policy has a huge performace impact. but you know, at a certain point it all dies anyway. Consider a recent project with over 1 billion records in the database. Cache hit rate is nil, either way. the only thing that helps there is elevator sorts and deep execution queues. ---------- Sincerely Yours, Simon Shapiro Shimon@Simon-Shapiro.ORG Voice: 503.799.2313 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message