Date: Wed, 18 Feb 1998 11:30:23 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Wilko Bulte <wilko@yedi.iaf.nl> Cc: freebsd-scsi@FreeBSD.ORG, curt@kcwc.com Subject: Re: getting oriented with RAID Message-ID: <XFMail.980218113023.shimon@simon-shapiro.org> In-Reply-To: <199802181850.TAA01578@yedi.iaf.nl>
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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
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