From: Dan Christensen <jdc@uwo.ca>
To: mingz@ele.uri.edu
Cc: Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: RAID-5 streaming read performance
Date: Wed, 13 Jul 2005 08:48:02 -0400 [thread overview]
Message-ID: <87eka2g9dp.fsf@uwo.ca> (raw)
In-Reply-To: <1121257494.5504.4.camel@localhost.localdomain>
Ming Zhang <mingz@ele.uri.edu> writes:
> have u try the parallel write?
I haven't tested it as thoroughly, as it brings lvm and the filesystem
into the mix. (The disks are in "production" use, and are fairly
full, so I can't do writes directly to the disk partitions/raid
device.)
My preliminary finding is that raid writes are faster than non-raid
writes: 49MB/s vs 39MB/s. Still not stellar performance, though.
Question for the list: if I'm doing a long sequential write, naively
each parity block will get recalculated and rewritten several times,
once for each non-parity block in the stripe. Does the write-caching
that the kernel does mean that each parity block will only get written
once?
Dan
next prev parent reply other threads:[~2005-07-13 12:48 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-11 15:11 RAID-5 streaming read performance Dan Christensen
2005-07-13 2:08 ` Ming Zhang
2005-07-13 2:52 ` Dan Christensen
2005-07-13 3:15 ` berk walker
2005-07-13 12:24 ` Ming Zhang
2005-07-13 12:48 ` Dan Christensen [this message]
2005-07-13 12:52 ` Ming Zhang
2005-07-13 14:23 ` Dan Christensen
2005-07-13 14:29 ` Ming Zhang
2005-07-13 17:56 ` Dan Christensen
2005-07-13 22:38 ` Neil Brown
2005-07-14 0:09 ` Ming Zhang
2005-07-14 1:16 ` Neil Brown
2005-07-14 1:25 ` Ming Zhang
2005-07-13 18:02 ` David Greaves
2005-07-13 18:14 ` Ming Zhang
2005-07-13 21:18 ` David Greaves
2005-07-13 21:44 ` Ming Zhang
2005-07-13 21:50 ` David Greaves
2005-07-13 21:55 ` Ming Zhang
2005-07-13 22:52 ` Neil Brown
2005-07-14 3:58 ` Dan Christensen
2005-07-14 4:13 ` Mark Hahn
2005-07-14 21:16 ` Dan Christensen
2005-07-14 21:30 ` Ming Zhang
2005-07-14 23:29 ` Mark Hahn
2005-07-15 1:23 ` Ming Zhang
2005-07-15 2:11 ` Dan Christensen
2005-07-15 12:28 ` Ming Zhang
2005-07-14 12:30 ` Ming Zhang
2005-07-14 14:23 ` Ming Zhang
2005-07-14 17:54 ` Dan Christensen
2005-07-14 18:00 ` Ming Zhang
2005-07-14 18:03 ` Dan Christensen
2005-07-14 18:10 ` Ming Zhang
2005-07-14 19:16 ` Dan Christensen
2005-07-14 20:13 ` Ming Zhang
2005-07-15 2:38 ` Dan Christensen
2005-07-15 6:01 ` Holger Kiehl
2005-07-15 12:29 ` Ming Zhang
2005-07-13 22:42 ` Neil Brown
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