From: Roman Mamedov <roman@rm.pp.ru>
To: Marco <jjletho67-diar@yahoo.it>
Cc: linux-raid@vger.kernel.org
Subject: Re: raid1 performance
Date: Sun, 25 Jul 2010 21:19:26 +0600 [thread overview]
Message-ID: <20100725211926.7547c12e@natsu> (raw)
In-Reply-To: <443220.14357.qm@web28508.mail.ukl.yahoo.com>
[-- Attachment #1: Type: text/plain, Size: 699 bytes --]
On Sun, 25 Jul 2010 14:58:37 +0000 (GMT)
Marco <jjletho67-diar@yahoo.it> wrote:
> doing a simple performance tests i obtained some very unexpected results: if
> i issue hdparm -t /dev/md2 i obtain 61 - 65 MB/s while issuing the same test
> directly on the partitions which compose md2 (/dev/sda3 and /dev/sdb3) i
> obtain 84 - 87 MB/s. I didn't expect a so big difference between md2 and one
> of its member. What can cause this difference ?
Maybe their read-ahead settings are different?
Check out "blockdev --getra /dev/md2", and compare that with the same
setting of the member disks. You can experiment with changing it by using
"--setra" as well.
--
With respect,
Roman
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 198 bytes --]
next prev parent reply other threads:[~2010-07-25 15:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-25 14:58 raid1 performance Marco
2010-07-25 15:19 ` Roman Mamedov [this message]
2010-07-26 9:37 ` Marco
2010-07-26 10:24 ` Keld Simonsen
2010-07-26 10:53 ` John Robinson
2010-07-26 11:30 ` Keld Simonsen
2010-07-27 16:10 ` Marco
2010-07-26 11:03 ` Neil Brown
2010-07-27 1:23 ` Leslie Rhorer
2010-07-27 16:10 ` Marco
2010-07-27 22:23 ` Neil Brown
2010-07-28 12:10 ` Marco
2010-07-28 12:24 ` Neil Brown
2010-07-31 15:21 ` Marco
2010-07-31 16:04 ` Keld Simonsen
-- strict thread matches above, loose matches on Subject: below --
2010-07-19 12:14 Marco
2004-04-21 5:57 RAID1: Performance Mike Mestnik
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100725211926.7547c12e@natsu \
--to=roman@rm.pp.ru \
--cc=jjletho67-diar@yahoo.it \
--cc=linux-raid@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox