I am running a server that has four 250 GB hard drives in a RAID 5 configuration. Recently, two of the hard drives failed. I copied the data bitwise from one of the failed hard drives (/dev/hdc1) to another (/dev/hdd1) using dd_rescue (http://www.garloff.de/kurt/linux/ddrescue/). The failed hard drive had about 300 bad blocks (I checked using the badblocks utility).
I tried to use the two new disks to recover the RAID data working on an assumption in the post:
http://www.spinics.net/lists/raid/msg03502.html
However, that didn't seem to work. I'd like to recover the data if possible, but I'm pretty sure I had all of it backed up. So, I just tried to force the creation of the array using mkraid /dev/md0 --really-force. That seemed to give me problems when running fsck, so I rebooted the server and tried creating the array using mdadm.
That is when I was getting the errors. Hopefully, this made things a bit clearer.
If you think I'm spamming on the list, you can mail me at sa@xxxxxxxxxxxxxxxxxxxx
Thanks, Saurabh.
On Oct 21, 2004, at 6:57 PM, Guy wrote:
You said: "Any advice on why my RAID array will not run?" Yes, you have 2 failed disks!
Number Major Minor RaidDevice State 0 22 1 0 active sync /dev/hdc1 1 22 65 1 faulty /dev/hdd1 2 0 0 2 faulty removed 3 34 65 3 active sync /dev/hdh1
4 34 1 4 spare /dev/hdg1
If you replaced 2 disks from a RAID5, then the data is lost! Are you sure this is what you wanted to do?
How did you assemble with 2 failed/replaced disks?
I am confused. Based on the output of "mdadm --detail", the array should be
down.
Do you want to recover the data? If yes then If you hope to save the data stop doing stuff! And don't lose the failed disks! They may not be bad. And label them so you know which is which, if not too late! If both disks are really bad (unreadable), then the data is gone. Post another message with the status of the failed disks. If no then Just recreate the array with the current disks and move on. Use mkfs to create a new filesystem.
Guy
-----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Saurabh Barve Sent: Thursday, October 21, 2004 6:55 PM To: linux-raid@xxxxxxxxxxxxxxx Subject: Persistent superblock error
Hi,
I recently lost 2 hard drives in my 4-drive RAID-5 array. I replaced the
two faulty hard drives and tried rebuilding the array. However, I
continue to get errors.
I created the raid array using madam: mdadm --assemble /dev/md0 --update=summaries /dev/hdc1 /dev/hdd1 /dev/hdg1 /dev/hdh1
I then tried to run fsck on /dev/md0 to make sure there were no file
system errors. However, fsck returned error messages that the number of
cylinders according to the superblock were 183833712, while the physical
size of the device was 183104736.
Running fdisk on /dev/md0 returned the following:
--------------
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF
disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
The number of cylinders for this disk is set to 183104736. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): p
Disk /dev/md0: 749.9 GB, 749996998656 bytes 2 heads, 4 sectors/track, 183104736 cylinders Units = cylinders of 8 * 512 = 4096 bytes ---------------
I tried inspecting the raid array with mdamd - 'mdadm --detail --test /dev/md0'. It gave me the following results: ------------------ /dev/md0: Version : 00.90.00 Creation Time : Thu Oct 21 16:27:20 2004 Raid Level : raid5 Array Size : 732418944 (698.49 GiB 749.100 GB) Device Size : 244139648 (232.83 GiB 249.100 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 0 Persistence : Superblock is persistent
Update Time : Thu Oct 21 16:38:59 2004 State : dirty, degraded Active Devices : 2 Working Devices : 3 Failed Devices : 1 Spare Devices : 1
Layout : left-symmetric Chunk Size : 64K
UUID : c7a73d47:a072c630:7693d236:dff40ca6 Events : 0.6
Number Major Minor RaidDevice State 0 22 1 0 active sync /dev/hdc1 1 22 65 1 faulty /dev/hdd1 2 0 0 2 faulty removed 3 34 65 3 active sync /dev/hdh1
4 34 1 4 spare /dev/hdg1 --------------------
My /etc/raidtab files reads like this:
--------- raiddev /dev/md0 raid-level 5 nr-raid-disks 4 nr-spare-disks 0 persistent-superblock 1 parity-algorithm left-symmetric chunk-size 64 device /dev/hdc1 raid-disk 0 device /dev/hdd1 raid-disk 1 device /dev/hdg1 raid-disk 2 device /dev/hdh1 raid-disk 3 ----------
Any advice on why my RAID array will not run?
Thanks, Saurabh.
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