From: Christoph Hellwig <hch@infradead.org>
To: Wolfgang Denk <wd@denx.de>
Cc: Christoph Hellwig <hch@infradead.org>, linux-raid@vger.kernel.org
Subject: Re: Optimize RAID0 for max IOPS?
Date: Tue, 25 Jan 2011 16:35:23 -0500 [thread overview]
Message-ID: <20110125213523.GA14375@infradead.org> (raw)
In-Reply-To: <20110125184115.1119FB187@gemini.denx.de>
On Tue, Jan 25, 2011 at 07:41:15PM +0100, Wolfgang Denk wrote:
> > I don't think you even want a RAID0 in that case. For small IOPs
> > you're much better off with a simple concatenation of devices.
>
> What exactly do you mean by "conatenation"? LVM striping?
> At least the discussion here does not show any significant advantages
> for this concept:
> http://groups.google.com/group/ubuntu-user-community/web/pick-your-pleasure-raid-0-mdadm-striping-or-lvm-striping
No, concatenation means not using any striping, but just concatenating
the disk linearly, e.g.
+-----------------------------------+
| Filesystem |
+--------+--------+--------+--------+
| Disk 1 | Disk 2 | Disk 3 | Disk 4 |
+--------+--------+--------+--------+
This can be done using the using the MD linear target, or simply
by having multiple PVs in a VG with LVM.
>
> > Make sure to disable the disk write caches and if not using the newest
> > kernel also mount the filesystem with -o nobarrier. With lots of small
> > I/Os and metadata intensive workloads that's usually a lot faster.
>
> Tests if done recently indicate that on the other hand nobarrier causes
> a serious degradation of read and write performance (down to some 40%
> of the values before).
Do you have a pointer to your results?
next prev parent reply other threads:[~2011-01-25 21:35 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-18 21:01 Optimize RAID0 for max IOPS? Wolfgang Denk
2011-01-18 22:18 ` Roberto Spadim
2011-01-19 7:04 ` Wolfgang Denk
2011-01-18 23:15 ` Stefan /*St0fF*/ Hübner
2011-01-19 0:05 ` Roberto Spadim
2011-01-19 7:11 ` Wolfgang Denk
2011-01-19 8:18 ` Stefan /*St0fF*/ Hübner
2011-01-19 8:29 ` Jaap Crezee
2011-01-19 9:32 ` Jan Kasprzak
2011-01-19 7:10 ` Wolfgang Denk
2011-01-19 19:21 ` Wolfgang Denk
2011-01-19 19:50 ` Roberto Spadim
2011-01-19 22:36 ` Stefan /*St0fF*/ Hübner
2011-01-19 23:09 ` Roberto Spadim
2011-01-19 23:18 ` Roberto Spadim
2011-01-20 2:48 ` Keld Jørn Simonsen
2011-01-20 3:53 ` Roberto Spadim
2011-01-21 19:34 ` Wolfgang Denk
2011-01-21 20:03 ` Roberto Spadim
2011-01-21 20:04 ` Roberto Spadim
2011-01-24 14:40 ` CoolCold
2011-01-24 15:25 ` Justin Piszcz
2011-01-24 20:48 ` Wolfgang Denk
2011-01-24 21:57 ` Wolfgang Denk
2011-01-24 23:03 ` Dave Chinner
2011-01-25 7:39 ` Emmanuel Florac
2011-01-25 8:36 ` Dave Chinner
2011-01-25 12:45 ` Wolfgang Denk
2011-01-25 12:51 ` Emmanuel Florac
2011-01-24 20:43 ` Wolfgang Denk
2011-01-25 17:10 ` Christoph Hellwig
2011-01-25 18:41 ` Wolfgang Denk
2011-01-25 21:35 ` Christoph Hellwig [this message]
2011-01-26 7:16 ` Wolfgang Denk
2011-01-26 8:32 ` Stan Hoeppner
2011-01-26 8:42 ` Wolfgang Denk
2011-01-26 9:38 ` Christoph Hellwig
2011-01-26 9:41 ` CoolCold
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