From: Chris Snook <csnook@redhat.com>
To: "Jens Bäckman" <jens.backman@gmail.com>
Cc: Justin Piszcz <jpiszcz@lucidpixels.com>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
xfs@oss.sgi.com
Subject: Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++)
Date: Wed, 28 May 2008 12:40:00 -0400 [thread overview]
Message-ID: <483D8AE0.8090606@redhat.com> (raw)
In-Reply-To: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com>
Jens Bäckman wrote:
> On Wed, May 28, 2008 at 10:53 AM, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
>> Results:
>>
>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html
>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt
>
> Either the RAID 1 read speed must be wrong, or something is odd in the
> Linux implementation. There's six drives that can be used for reading
> at the same time, as they contain the very same data. 63MB/s
> sequential looks like what you would get from a single drive.
The test is a single thread reading one block at a time, so this is not
surprising. If you get this doing multi-megabyte readahead, or with
several threads, something is very wrong.
-- Chris
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WARNING: multiple messages have this Message-ID (diff)
From: Chris Snook <csnook@redhat.com>
To: "Jens Bäckman" <jens.backman@gmail.com>
Cc: Justin Piszcz <jpiszcz@lucidpixels.com>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
xfs@oss.sgi.com
Subject: Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++)
Date: Wed, 28 May 2008 12:40:00 -0400 [thread overview]
Message-ID: <483D8AE0.8090606@redhat.com> (raw)
In-Reply-To: <95711f160805280934y77ed7d91tec5aeb531bf8013c@mail.gmail.com>
Jens Bäckman wrote:
> On Wed, May 28, 2008 at 10:53 AM, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
>> Results:
>>
>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html
>> http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt
>
> Either the RAID 1 read speed must be wrong, or something is odd in the
> Linux implementation. There's six drives that can be used for reading
> at the same time, as they contain the very same data. 63MB/s
> sequential looks like what you would get from a single drive.
The test is a single thread reading one block at a time, so this is not
surprising. If you get this doing multi-megabyte readahead, or with
several threads, something is very wrong.
-- Chris
next prev parent reply other threads:[~2008-05-28 16:40 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-28 8:53 Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) Justin Piszcz
2008-05-28 10:54 ` Peter Rabbitson
2008-05-28 11:05 ` Justin Piszcz
2008-05-28 15:40 ` Chris Snook
2008-05-28 17:32 ` Justin Piszcz
2008-05-28 17:53 ` Justin Piszcz
2008-05-28 19:22 ` Chris Snook
2008-05-28 19:27 ` Justin Piszcz
2008-05-29 9:57 ` Kasper Sandberg
2008-05-29 21:08 ` Justin Piszcz
2008-05-28 20:03 ` Richard Scobie
2008-05-28 20:01 ` Justin Piszcz
2008-05-28 16:34 ` Jens Bäckman
2008-05-28 16:40 ` Chris Snook [this message]
2008-05-28 16:40 ` Chris Snook
2008-05-28 16:46 ` Bryan Mesich
2008-05-28 16:46 ` Bryan Mesich
2008-05-28 17:33 ` Justin Piszcz
2008-05-28 18:57 ` Alan Cox
2008-05-28 18:57 ` Alan Cox
2008-05-28 23:00 ` Bill Davidsen
2008-05-28 23:00 ` Bill Davidsen
2008-05-29 11:22 ` Alan Cox
2008-05-30 12:22 ` Bill Davidsen
2008-05-28 19:02 ` Keld Jørn Simonsen
2008-05-28 19:05 ` Justin Piszcz
2008-05-28 23:09 ` Bill Davidsen
2008-05-29 6:37 ` Michal Soltys
2008-05-29 6:44 ` Holger Kiehl
2008-05-29 12:06 ` Justin Piszcz
2008-05-29 17:02 ` Justin Piszcz
2008-05-30 12:55 ` Bill Davidsen
2008-05-30 14:23 ` Keld Jørn Simonsen
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