*BSD News Article 89193


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From: ajudge@maths.tcd.ie (Alan Judge)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: FreeBSD 2.1.6 Striping Performance
Date: 10 Feb 1997 11:21:10 -0000
Organization: Dept. of Maths, Trinity College, Dublin, Ireland.
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craigs@os.com (Craig Shrimpton) writes:
>Several people have suggested that one should use the maximum interleave
>(65536) for a news spool.  The theory is that the interleave should be 1
>disk cylinder.

Yep, I'd guess that the numbers should be different for news, where
small file I/O matters and sequential performance doesn't.  I don't
have any experience here myself, but I would be interested in hearing
what you find out as I'll be setting up a CCD based news system soon.

A possible value might be 4096 (the size of a notional cylinder from
CCD) or 65536 (the size of a cylinder group).

I've also found that adjusting the interleave so that it doesn't
divide evenly into 4096 can be a good idea.  Otherwise, disk 0 in the
stripe bears a lot of the meta-information load.  (Watch what fsck or
newfs does to the disks for an interleave of 128 and then 127.)
-- 
Alan Judge 

Like punning, programming is a play on words.   -- Alan Perlis