From: "Keld Jørn Simonsen" <keld@keldix.com>
To: "Keld Jørn Simonsen" <keld@keldix.com>
Cc: David Brown <david@westcontrol.com>, linux-raid@vger.kernel.org
Subject: Re: What's the typical RAID10 setup?
Date: Tue, 1 Feb 2011 21:32:10 +0100 [thread overview]
Message-ID: <20110201203210.GB26468@www2.open-std.org> (raw)
In-Reply-To: <20110201160245.GA25659@www2.open-std.org>
On Tue, Feb 01, 2011 at 05:02:46PM +0100, Keld Jørn Simonsen wrote:
> On Tue, Feb 01, 2011 at 11:01:33AM +0100, David Brown wrote:
> > On 31/01/2011 23:52, Keld Jørn Simonsen wrote:
> > >raid1+0 and Linux MD raid10 are similar, but significantly different
> > >in a number of ways. Linux MD raid10 can run on only 2 drives.
> > >Linux raid10,f2 has almost RAID0 striping performance in sequential read.
> > >You can have an odd number of drives in raid10.
> > >And you can have as many copies as you like in raid10,
> > >
> >
> > You can make raid10,f2 functionality from raid1+0 by using partitions.
> > For example, to get a raid10,f2 equivalent on two drives, partition them
> > into equal halves. Then make md0 a raid1 mirror of sda1 and sdb2, and
> > md1 a raid1 mirror of sdb1 and sda2. Finally, make md2 a raid0 stripe
> > set of md0 and md1.
>
> I don't think you get the striping performance of raid10,f2 with this
> layout. And that is one of the main advantages of raid10,f2 layout.
> Have you tried it out?
>
> As far as I can see the layout of blocks are not alternating between the
> disks. You have one raid1 of sda1 and sdb2, there a file is allocated on
> blocks sequentially on sda1 and then mirrored on sdb2, where it is also
> sequentially allocated. That gives no striping.
Well, maybe the RAID0 layer provides the adequate striping.
I am noy sure, but it looks like it could hold in theory.
One could try it out.
One advantage of this scheme could be improved probability
When 2 drives fail, eg. in the case of a 4 drive array.
The probability of survival of a running system could then
be enhaced form 33 % to 66 %.
One problem could be the choice of always the lowest block number, which
is secured in raid10,f2, but not in a raid0 over raid1 (or raid10,n2) scenario.
best regards
keld
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next prev parent reply other threads:[~2011-02-01 20:32 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-31 9:41 What's the typical RAID10 setup? Mathias Burén
2011-01-31 10:14 ` Robin Hill
2011-01-31 10:22 ` Mathias Burén
2011-01-31 10:36 ` CoolCold
2011-01-31 15:00 ` Roberto Spadim
2011-01-31 15:21 ` Robin Hill
2011-01-31 15:27 ` Roberto Spadim
2011-01-31 15:28 ` Roberto Spadim
2011-01-31 15:32 ` Roberto Spadim
2011-01-31 15:34 ` Roberto Spadim
2011-01-31 15:37 ` Roberto Spadim
2011-01-31 15:45 ` Robin Hill
2011-01-31 16:55 ` Denis
2011-01-31 17:31 ` Roberto Spadim
2011-01-31 18:35 ` Denis
2011-01-31 19:15 ` Roberto Spadim
2011-01-31 19:28 ` Keld Jørn Simonsen
2011-01-31 19:35 ` Roberto Spadim
2011-01-31 19:37 ` Roberto Spadim
2011-01-31 20:22 ` Keld Jørn Simonsen
2011-01-31 20:17 ` Stan Hoeppner
2011-01-31 20:37 ` Keld Jørn Simonsen
2011-01-31 21:20 ` Roberto Spadim
2011-01-31 21:24 ` Mathias Burén
2011-01-31 21:27 ` Jon Nelson
2011-01-31 21:47 ` Roberto Spadim
2011-01-31 21:51 ` Roberto Spadim
2011-01-31 22:50 ` NeilBrown
2011-01-31 22:53 ` Roberto Spadim
2011-01-31 23:10 ` NeilBrown
2011-01-31 23:14 ` Roberto Spadim
2011-01-31 22:52 ` Keld Jørn Simonsen
2011-01-31 23:00 ` Roberto Spadim
2011-02-01 10:01 ` David Brown
2011-02-01 13:50 ` Jon Nelson
2011-02-01 14:25 ` Roberto Spadim
2011-02-01 14:48 ` David Brown
2011-02-01 15:41 ` Roberto Spadim
2011-02-03 3:36 ` Drew
2011-02-03 8:18 ` Stan Hoeppner
[not found] ` <AANLkTikerSZfhMbkEvGBVyLB=wHDSHLWszoEz5As5Hi4@mail.gmail.com>
[not found] ` <AANLkTikLyR206x4aMy+veNkWPV67uF9r5dZKGqXJUEqN@mail.gmail.com>
2011-02-03 14:35 ` Roberto Spadim
2011-02-03 15:43 ` Keld Jørn Simonsen
2011-02-03 15:50 ` Roberto Spadim
2011-02-03 15:54 ` Roberto Spadim
2011-02-03 16:02 ` Keld Jørn Simonsen
2011-02-03 16:07 ` Roberto Spadim
2011-02-03 16:16 ` Roberto Spadim
2011-02-01 22:05 ` Stan Hoeppner
2011-02-01 23:12 ` Roberto Spadim
2011-02-02 9:25 ` Robin Hill
2011-02-02 16:00 ` Roberto Spadim
2011-02-02 16:06 ` Roberto Spadim
2011-02-02 16:07 ` Roberto Spadim
2011-02-02 16:10 ` Roberto Spadim
2011-02-02 16:13 ` Roberto Spadim
2011-02-02 19:44 ` Keld Jørn Simonsen
2011-02-02 20:28 ` Roberto Spadim
2011-02-02 21:31 ` Roberto Spadim
2011-02-02 22:13 ` Keld Jørn Simonsen
2011-02-02 22:26 ` Roberto Spadim
2011-02-03 1:57 ` Roberto Spadim
2011-02-03 3:05 ` Stan Hoeppner
2011-02-03 3:13 ` Roberto Spadim
2011-02-03 3:17 ` Roberto Spadim
2011-02-01 23:35 ` Keld Jørn Simonsen
2011-02-01 16:02 ` Keld Jørn Simonsen
2011-02-01 16:24 ` Roberto Spadim
2011-02-01 17:56 ` Keld Jørn Simonsen
2011-02-01 18:09 ` Roberto Spadim
2011-02-01 20:16 ` Keld Jørn Simonsen
2011-02-01 20:32 ` Keld Jørn Simonsen [this message]
2011-02-01 20:58 ` Roberto Spadim
2011-02-01 21:04 ` Roberto Spadim
2011-02-01 21:18 ` David Brown
2011-02-01 0:58 ` Stan Hoeppner
2011-02-01 12:50 ` Roman Mamedov
2011-02-03 11:04 ` Keld Jørn Simonsen
2011-02-03 14:17 ` Roberto Spadim
2011-02-03 15:54 ` Keld Jørn Simonsen
2011-02-03 18:39 ` Keld Jørn Simonsen
2011-02-03 18:41 ` Roberto Spadim
2011-02-03 23:43 ` Stan Hoeppner
2011-02-04 3:49 ` hansbkk
2011-02-04 7:06 ` Keld Jørn Simonsen
2011-02-04 8:27 ` Stan Hoeppner
2011-02-04 9:06 ` Keld Jørn Simonsen
2011-02-04 10:04 ` Stan Hoeppner
2011-02-04 11:15 ` hansbkk
2011-02-04 13:33 ` Keld Jørn Simonsen
2011-02-04 20:35 ` Keld Jørn Simonsen
2011-02-04 20:42 ` Keld Jørn Simonsen
2011-02-04 21:15 ` Stan Hoeppner
2011-02-04 22:05 ` Keld Jørn Simonsen
2011-02-04 23:03 ` Stan Hoeppner
2011-02-06 3:59 ` Drew
2011-02-06 4:27 ` Stan Hoeppner
2011-02-04 11:34 ` David Brown
2011-02-04 13:53 ` Keld Jørn Simonsen
2011-02-04 14:17 ` David Brown
2011-02-04 14:21 ` hansbkk
2011-02-06 4:02 ` Drew
2011-02-06 7:58 ` Keld Jørn Simonsen
2011-02-06 12:03 ` Roman Mamedov
2011-02-06 14:30 ` Roberto Spadim
2011-02-01 8:46 ` hansbkk
2011-01-31 19:37 ` Phillip Susi
2011-01-31 19:41 ` Roberto Spadim
2011-01-31 19:46 ` Phillip Susi
2011-01-31 19:53 ` Roberto Spadim
2011-01-31 22:10 ` Phillip Susi
2011-01-31 22:14 ` Denis
2011-01-31 22:33 ` Roberto Spadim
2011-01-31 22:36 ` Roberto Spadim
2011-01-31 20:23 ` Stan Hoeppner
2011-01-31 21:59 ` Phillip Susi
2011-01-31 22:08 ` Jon Nelson
2011-01-31 22:38 ` Phillip Susi
2011-02-01 10:05 ` David Brown
2011-02-01 9:20 ` Robin Hill
2011-02-04 16:03 ` Phillip Susi
2011-02-04 16:22 ` Robin Hill
2011-02-04 20:35 ` [OT] " Phil Turmel
2011-02-04 20:35 ` Phillip Susi
2011-02-04 21:05 ` Stan Hoeppner
2011-02-04 21:13 ` Roberto Spadim
2011-01-31 15:30 ` Robin Hill
2011-01-31 20:07 ` Stan Hoeppner
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