From: Neil Brown <neilb@suse.de>
To: "Patrick J. LoPresti" <lopresti@gmail.com>
Cc: ocfs2-users@oss.oracle.com, linux-raid@vger.kernel.org
Subject: Re: Combining OCFS2 with Linux software RAID-0?
Date: Thu, 10 Dec 2009 12:37:03 +1100 [thread overview]
Message-ID: <20091210123703.71b47ce7@notabene.brown> (raw)
In-Reply-To: <23986fd90912091503r3c671448va4d8637edfab472b@mail.gmail.com>
On Wed, 9 Dec 2009 15:03:11 -0800
"Patrick J. LoPresti" <lopresti@gmail.com> wrote:
> Is it possible to run an OCFS2 file system on top of Linux software RAID?
>
> Here is my situation. I have four identical disk chassis that perform
> hardware RAID internally. Each chassis has a pair of fiber channel
> ports, and I can assign the same LUN to both ports. I want to connect
> all of these chassis to two Linux systems. I want the two Linux
> systems to share a file system that is striped across all four chassis
> for performance.
>
> I know I can use software RAID (mdadm) to do RAID-0 striping across
> the four chassis on a single machine; I have tried this, it works
> fine, and the performance is tremendous. I also know I can use OCFS2
> to create a single filesystem on a single chassis that is shared
> between my two Linux systems. What I want is to combine these two
> things.
>
> Suse's documentation
> (http://www.novell.com/documentation/sles11/stor_admin/?page=/documentation/sles11/stor_admin/data/raidyast.html)
> says:
>
> "IMPORTANT:Software RAID is not supported underneath clustered file
> systems such as OCFS2, because RAID does not support concurrent
> activation. If you want RAID for OCFS2, you need the RAID to be
> handled by the storage subsystem."
>
> Because my disk chassis already perform hardware RAID-5, I only need
> Linux to do the striping (RAID-0) in software. So for me, there is no
> issue about "which node should rebuild the RAID" etc. I understand
> that Linux md stores meta-data on the partitions and is not cluster
> aware, but will this create problems for OCFS2 even if it is just RAID
> 0?
>
> Has anybody tried something like this? Are there alternative RAID-0
> solutions for Linux that would be expected to work?
For RAID0 or LINEAR, this should work - give it a try.
If it doesn't work in some way, let me know and I'll see about fixing it.
It might work for RAID1 one day to, but is unlikely to ever work for
RAID5.
NeilBrown
next prev parent reply other threads:[~2009-12-10 1:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-09 23:03 Combining OCFS2 with Linux software RAID-0? Patrick J. LoPresti
2009-12-10 1:37 ` Neil Brown [this message]
2009-12-11 7:15 ` Luca Berra
2009-12-11 7:30 ` Wolfgang Denk
2009-12-11 13:37 ` Luca Berra
2009-12-11 7:33 ` Neil Brown
2009-12-10 19:40 ` [Ocfs2-users] " Sunil Mushran
2009-12-10 21:45 ` Joel Becker
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