From: David Greaves <david@dgreaves.com>
To: mingz@ele.uri.edu
Cc: Dan Christensen <jdc@uwo.ca>, Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: RAID-5 streaming read performance
Date: Wed, 13 Jul 2005 22:18:57 +0100 [thread overview]
Message-ID: <42D58541.7000702@dgreaves.com> (raw)
In-Reply-To: <1121278451.5504.79.camel@localhost.localdomain>
Ming Zhang wrote:
>>component partitions, e.g. /dev/sda7: 39MB/s
>>raid device /dev/md2: 31MB/s
>>lvm device /dev/main/media: 53MB/s
>>
>>(oldish system - but note that lvm device is *much* faster)
>>
>>
>
>this is so interesting to see! seems that some read ahead parameters
>have negative impact.
>
>
I guess each raw device does some readahead, then the md0 does some
readahead and then the lvm does some readahead. Theoretically the md0
and lvm should overlap - but I guess that much of the raw device level
readahead is discarded.
David
--
next prev parent reply other threads:[~2005-07-13 21:18 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
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 [this message]
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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