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From: jthomp@convexs.UUCP
Newsgroups: comp.arch
Subject: Re: Disk Striping (description and
Message-ID: <116200003@convexs>
Date: Wed, 26-Aug-87 01:34:00 EDT
Article-I.D.: convexs.116200003
Posted: Wed Aug 26 01:34:00 1987
Date-Received: Sat, 19-Sep-87 11:36:41 EDT
References: <898@homxc.UUCP>
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Nf-ID: #R:homxc.UUCP:-89800:convexs:116200003:000:1130
Nf-From: convexs.UUCP!jthomp    Aug 26 00:34:00 1987


/* Written  3:10 pm  Aug 14, 1987 by dwc@homxc.UUCP in convexs:comp.arch */
/* ---------- "Re: Disk Striping (description and" ---------- */
In article <3721@well.UUCP>, rchrd@well.UUCP writes:
> 
> One more comment about disk striping:  there is a real limiting

can't you seal the disk in a vacuum?  isn't that what happens in
winchesters?  i don't know, just asking.

nope, no air, no head gap ---> no disk....

> you achieve a kind of parallelism in I/O.  I have written some
> software packages using asynch I/O on the Cray that attempt this
> sort of thing and it is very successful for large blocks of data.

i was doing a quick analysis of disk stripping and made a small
observation:  with multiple disks, the average rotational latency
approches that of an entire rotation instead of 1/2 or 1/3 rotation
(i forget the numbers).

Not if you configure things correctly!
someone at your site should use 'tunefs' to put the correct numbers
for the 'rotdelay' parameter...

(in a super-secret project here, we're making dump go fast, fast, fast.)
(I can't give numbers now...  but its GREAT!)

Jim Thompson (jthomp@convex)