To avoid confusion, the paragraph I wrote is in context of ASM's
management of superblock, not OCFS2. OCFS2 was already responded to by
Sunil in another reply.
Regards,
Saar.
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On Thu, 13 Dec 2007, Saar Maoz wrote:
Date: Thu, 13 Dec 2007 20:28:44 +0200 (Jerusalem Standard Time)
From: Saar Maoz <[EMAIL PROTECTED]>
To: Jeremy Schneider <[EMAIL PROTECTED]>
Cc: [email protected]
Subject: Re: [Ocfs2-users] superblock backups, ASM vs OCFS2
Jermey,
In 11.1.0.7 (and beyond) we will have a backup of the disk header (the first
4k). Prior to that, we have been able in most circumstances to reconstruct
the disk header using KFED. KFED will still be the tool to restore the disk
header going forward, it will just be a simpler, more reliable procedure.
Regards,
Saar.
--
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(( /\\ /\\ ||) |\V/| /\\ /\\ >/ Consulting Software Engineer
_))//-\\//-\\||\ |||||//-\\\\//<_ Oracle Corporation
HQ: 650.50-mixOS WK: 510.222.4224 [EMAIL PROTECTED] 4op441
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///Share your knowledge with others and compete with yourself///
On Thu, 13 Dec 2007, Jeremy Schneider wrote:
Date: Thu, 13 Dec 2007 10:58:44 -0600
From: Jeremy Schneider <[EMAIL PROTECTED]>
To: [email protected]
Subject: [Ocfs2-users] superblock backups, ASM vs OCFS2
[Also posted to Oracle-L]
Just wondering, does anyone know much about "superblock" backups in ASM vs
OCFS2?
I ran into an interesting case a month or so back where someone had
accidentally tried to initialize their ASM disks with linux LVM... and
written the LVM headers to the disk. It was just a few bytes at the very
top of the disk - but it was enough to totally hose ASM. Which started me
thinking, "if this was a filesystem then I'd have a backup superblock that
I
could recover". Who knows - maybe ASM has a backup of its header block -
but it's all proprietary and if there's a tool that will recover an ASM
header then it's probably buried at Oracle support somewhere.
Looks like OCFS2 includes superblock backups since this patchset:
http://lkml.org/lkml/2007/1/22/148
Not sure if ckfs will recover them but since it's open source it'd be
trivial to put together a utility that would recover a superblock.
This seems to me to be a great reason to choose OCFS2 over ASM. Recovering
a backup superblock is MUCH faster than recreating the entire volume and
restoring data from backup!!! I don't even know if you could use dd to try
to backup your ASM disk headers - since it's proprietary I don't know
what's
in those blocks.
Anyone have any thoughts on this? Is there anything I'm missing here?
Jeremy
--
Jeremy Schneider
Chicago, IL
http://www.ardentperf.com/category/technical
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