[Ocfs2-users] superblock backups, ASM vs OCFS2

[Saar Maoz]

ASM related:

no, md_backup/md_restore just handles the ASM diskgroup attributes, as 
mentioned before, in 11.1.0.7 (which is 11g) KFED will handle the 
superblock recovery.

Regards,

Saar.

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On Thu, 13 Dec 2007, Jeremy Schneider wrote:

> Date: Thu, 13 Dec 2007 14:33:21 -0600
> From: Jeremy Schneider <jeremy.schneider at ardentperf.com>
> To: Saar.Maoz at oracle.com
> Cc: ocfs2-users at oss.oracle.com
> Subject: Re: [Ocfs2-users] superblock backups, ASM vs OCFS2
> 
> Sunil and Saar - thanks for the quick replies!!
>
> Quick follow-up question: would the 11g asmcmd "md_backup" command also be
> able to quickly rebuild all of the disk header information without losing
> any data?
>
>
> On 12/13/07, Saar Maoz <Saar.Maoz at oracle.com> wrote:
>>
>>
>> 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.
>>
>> --
>>    __  _    _  __    _ _   _   _ ___ _____________________________
>>   ((  /\\  /\\ ||)  |\V/| /\\ /\\ >/ Consulting Software Engineer
>>   _))//-\\//-\\||\  |||||//-\\\\//<_ Oracle Corporation
>>   HQ: 650.50-mixOS  WK: 510.222.4224 Saar.Maoz at oracle.com  4op441
>>   \\\\\\\\50-64967\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
>>   ///Share your knowledge with others and compete with yourself///
>>
>>
>> On Thu, 13 Dec 2007, Saar Maoz wrote:
>>
>>> Date: Thu, 13 Dec 2007 20:28:44 +0200 (Jerusalem Standard Time)
>>> From: Saar Maoz <Saar.Maoz at oracle.com>
>>> To: Jeremy Schneider <jeremy.schneider at ardentperf.com>
>>> Cc: ocfs2-users at oss.oracle.com
>>> 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.
>>>
>>> --
>>>  __  _    _  __    _ _   _   _ ___ _____________________________
>>> ((  /\\  /\\ ||)  |\V/| /\\ /\\ >/ Consulting Software Engineer
>>> _))//-\\//-\\||\  |||||//-\\\\//<_ Oracle Corporation
>>> HQ: 650.50-mixOS  WK: 510.222.4224 Saar.Maoz at oracle.com  4op441
>>> \\\\\\\\50-64967\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
>>> ///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 <jeremy.schneider at ardentperf.com>
>>>> To: ocfs2-users at oss.oracle.com
>>>> 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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>
>
> -- 
> Jeremy Schneider
> Chicago, IL
> http://www.ardentperf.com/category/technical
>
>