From: Mike Fedyk <mfedyk@matchmail.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Helge Hafting <helgehaf@aitel.hist.no>,
jw schultz <jw@pegasys.ws>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: raid0 slower than devices it is assembled of?
Date: Tue, 16 Dec 2003 12:58:53 -0800 [thread overview]
Message-ID: <20031216205853.GC1402@matchmail.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0312160825570.1599@home.osdl.org>
On Tue, Dec 16, 2003 at 08:42:52AM -0800, Linus Torvalds wrote:
> My personal guess is that modern RAID0 stripes should be on the order of
> several MEGABYTES in size rather than the few hundred kB that most people
> use (not to mention the people who have 32kB stripes or smaller - they
> just kill their IO access patterns with that, and put the CPU at
> ridiculous strain).
Larger stripes may help in general, but I'd suggest that for raid5 (ie, not
raid0), the stripe size should not be enlarged as much. On many
filesystems, a bitmap change, or inode table update shouldn't require
reading a large stripe from several drives to complete the pairity
calculations.
Probably finding the largest block of data the drive can return in one
command would be a good size for a raid5 stripe. That's just speculation
though.
next prev parent reply other threads:[~2003-12-16 20:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-15 13:34 raid0 slower than devices it is assembled of? Witold Krecicki
2003-12-15 15:44 ` Witold Krecicki
2003-12-16 4:01 ` jw schultz
2003-12-16 14:51 ` Helge Hafting
2003-12-16 16:42 ` Linus Torvalds
2003-12-16 20:58 ` Mike Fedyk [this message]
2003-12-16 21:11 ` Linus Torvalds
2003-12-17 10:53 ` Jörn Engel
2003-12-17 11:39 ` Peter Zaitsev
2003-12-17 16:01 ` Linus Torvalds
2003-12-17 18:37 ` Mike Fedyk
2003-12-17 21:55 ` bill davidsen
2003-12-17 17:02 ` bill davidsen
2003-12-17 20:14 ` Peter Zaitsev
2003-12-17 19:22 ` Jamie Lokier
2003-12-17 19:40 ` Linus Torvalds
2003-12-17 22:36 ` bill davidsen
2003-12-18 2:47 ` jw schultz
2003-12-17 22:29 ` bill davidsen
2003-12-18 2:18 ` jw schultz
2004-01-08 4:54 ` Greg Stark
2003-12-16 20:51 ` Andre Hedrick
2003-12-16 21:04 ` Andre Hedrick
2003-12-16 21:46 ` Witold Krecicki
2003-12-16 20:09 ` Witold Krecicki
2003-12-16 21:11 ` Adam Kropelin
2003-12-16 21:25 ` jw schultz
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