[Ocfs2-users] Partition table crash, where can I find debug message?

[Sunil Mushran]

extent of the corruption... (not crash)

On 10/12/2011 10:51 AM, Sunil Mushran wrote:
> Hard to say. You'll need to investigate the extent of the crash.
>
> On 10/12/2011 10:49 AM, Frank Zhang wrote:
>>
>> Sorry, it's not power outage, it's just a normal reboot.
>>
>> Is this serious to corrupt the super block?
>>
>> *From:*Frank Zhang
>> *Sent:* Wednesday, October 12, 2011 10:37 AM
>> *To:* 'Sunil Mushran'
>> *Cc:* 'ocfs2-users at oss.oracle.com'
>> *Subject:* RE: [Ocfs2-users] Partition table crash, where can I find debug message?
>>
>> Thanks Suni. Yes the terminology should be super block corruption.
>>
>> I checked with my colleague they said  the ISCSI server suffered a power outage yesterday so they rebooted it.
>>
>> Given it was under heavy usage because of many VM running on, I guess this may be the cause. now I am trying to recover it
>>
>> *From:*Sunil Mushran [mailto:sunil.mushran at oracle.com] <mailto:[mailto:sunil.mushran at oracle.com]>
>> *Sent:* Wednesday, October 12, 2011 10:08 AM
>> *To:* Frank Zhang
>> *Cc:* 'ocfs2-users at oss.oracle.com'
>> *Subject:* Re: [Ocfs2-users] Partition table crash, where can I find debug message?
>>
>> Not sure what you mean by a partition table crash. Is it that someone
>> overwrote the partition table on the iscsi server? That's what it looks
>> like. If mount cannot detect the fs type, then it means atleast superblock
>> corruption. And such corruptions typically caused by external entities.
>> Stray dd perhaps.
>>
>> Did you try recovering the superblock using one of the the backups?
>> fsck.ocfs2 -r [1-6] /dev/sdX ?
>>
>> On 10/11/2011 07:04 PM, Frank Zhang wrote:
>>
>> Hi Experts, recently I observed a partition table crash that made me really scared.
>>
>> I have two OVM servers sharing OCFS2 over iscsi, after running  a bunch of VMs for a while,  all VMs were gone and I saw the mount points of OCFS2 gone on both hosts.
>>
>> Then I tried to mount it again, the iscsi device crashed by saying "please specify filesystem type". I checked dmesg but there is nothing useful except
>>
>> "SCSI device sdc: drive cache: write back
>>
>> sdc: unknown partition table
>>
>> sd 2:0:0:1: Attached scsi disk sdc
>>
>> sd 2:0:0:1: Attached scsi generic sg3 type 0
>>
>> OCFS2 Node Manager 1.4.4
>>
>> OCFS2 DLM 1.4.4
>>
>> OCFS2 DLMFS 1.4.4
>>
>> OCFS2 User DLM kernel interface loaded
>>
>> connection1:0: detected conn error (1011)"
>>
>> basically after logging into ISCSI device on both hosts, I created soft links of /dev/ovm_iscsi1 pointing to device node under /dev/disk/by-path/real_isci_device, then I formatted /dev/ovm_iscsi1 to OCFS2 and mounted them to somewhere(of course I configured /etc/ocfs2/cluster.conf and made o2cb correctly start).
>>
>> Could somebody tell me where to get more debug info to trace the problem? This is really scared considering I may lose all my VMs because of the silent crash.
>>
>> And is there any way to recover the partition table? Thanks
>>
>>   
>>   
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>
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