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Old 10-17-2008, 05:28 PM   #1
eklingman
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Registered: Oct 2008
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Restore Hardware RAID Partition Table after power failure


Hi all,

I have a Dell PowerEdge 2950 connected to a PowerVault MD1000. Last night there was a power failure and when we tried to start it up this morning, fsck failed with the unhelpful "cannot continue, aborting."

After trying various things, I booted from a LiveCD and commented out all the RAID entries in /etc/fstab, and it started up okay. The problem is when I run an fdisk -l, here's the output:

Disk /dev/sda: 72.7 GB, 72746008576 bytes
255 heads, 63 sectors/track, 8844 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 8844 70935007+ 8e Linux LVM

Disk /dev/sdb: 3892.7 GB, 3892716765184 bytes
255 heads, 63 sectors/track, 473262 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table


/dev/sda is the internal drive, which functions fine. /dev/sdb is the hardware RAID in the PowerVault. sfdisk gives similar info:


Disk /dev/sdb: 473262 cylinders, 255 heads, 63 sectors/track

sfdisk: ERROR: sector 0 does not have an msdos signature
/dev/sdb: unrecognized partition table type
No partitions found





Here is the fstab:

/dev/VolGroup_System/LogVol_System / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup_System/LogVol_Swap swap swap defaults 0 0
#/dev/VolGroup_Data/LogVol_Home /volumes/home ext3 defaults 1 2
#/dev/VolGroup_Data/LogVol_Bin /volumes/brain-bin ext3 defaults 1 2
#/dev/VolGroup_Data/LogVol_Data /data ext3 defaults 1 2



Notice the three commented-out mounts; when I mount them manually they work fine and the data is intact. I'm just wary to pronounce the thing fixed and tell employees they can start using it again when the partition table isn't valid.

The OS is CentOS 5.2, and the kernel is 2.6.18-92.1.13.el5. For what it's worth, I ran testdisk twice; once with a partition table type of "None" and the 2nd time with the type "Intel," which is what it should be. The first time it found the partition but couldn't write it because the type was "None," and the second time it seemed to write it okay but it didn't fix it.

Also, for what it's worth, here's the relevant output from dmesg:

sdb : very big device. try to use READ CAPACITY(16).
SCSI device sdb: 7602962432 512-byte hdwr sectors (3892717 MB)
sdb: Write Protect is off
sdb: Mode Sense: 1f 00 00 08
SCSI device sdb: drive cache: write back, no read (daft)
sdb : very big device. try to use READ CAPACITY(16).
SCSI device sdb: 7602962432 512-byte hdwr sectors (3892717 MB)
sdb: Write Protect is off
sdb: Mode Sense: 1f 00 00 08
SCSI device sdb: drive cache: write back, no read (daft)
sdb: unknown partition table
sd 1:2:0:0: Attached scsi disk sdb




I'm a relative beginner when it comes to hardware raid, so any help is greatly appreciated, natch.
 
Old 10-17-2008, 06:07 PM   #2
Quakeboy02
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Registered: Nov 2006
Distribution: Debian Squeeze 2.6.32.9 SMP AMD64
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If you have paid support, now is surely the time to use it.

Barring that and given the severity of your error and the fact that you can still access the data (for the moment) you might want to start making backups while there's still data to backup.

If someone can give him some real help, please do so. I don't have much else to contribute.
 
Old 10-17-2008, 06:23 PM   #3
eklingman
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Registered: Oct 2008
Posts: 3

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Haha paid support, I wish! I'm actually doing this on a consulting basis, so I don't know what all they have going on with any vendors, but I'm sure there's no paid support.

Thankfully we do have backups from last night, I just would rather not have to re-set up the entire RAID array from scratch.
 
Old 10-17-2008, 07:26 PM   #4
Quakeboy02
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Registered: Nov 2006
Distribution: Debian Squeeze 2.6.32.9 SMP AMD64
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Do they have a spare raid controller card, so you could at least swap that out to make sure it's not that simple? You might also bring the raid down and look through the utilities to see if there's anything promising. Is the Powervault MD1000 a separate device? If so, was it booted properly before you brought up the server connected to it?

Here is a set of manuals for the MD1000:

http://support.dell.com/support/edoc...0/en/index.htm

Be warned, I know nothing about hardware raid, as I stated from the beginning. You break it, you buy it.
 
Old 09-23-2009, 09:12 AM   #5
JohnnyTsunami
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Registered: Sep 2009
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I have the same issue.
Is there any chance that this got solved?
If so, how?
 
Old 09-23-2009, 11:52 AM   #6
eklingman
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Registered: Oct 2008
Posts: 3

Original Poster
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Johnny,

It turned out not to be a problem in this case; the RAID had and has no partition table, and that's the way it was set up, and I mistakenly assumed it was a problem. If you are having trouble starting up I would suggest booting from a Live CD and running fsck to try and fix any filesystem errors.
 
  


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