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deadball
April 14th, 2010, 11:21 AM
Hey guys.

I've got a problem here:

One of my raid disks (was a software raid5 with 4 drives) failured. I wanted to buy a new 1.5TB harddisk anyway so i i copied all the Raid data onto the new disk and disconnected the old ones.

But then the new Disc crashed right before i could mirror it with another 1.5TB disk.

So i need to reassemble my old Raid 5 now.

I connected the drives in the former order except the first one, because this was the failed disk.

The problem is, mdadm can't find the raid, no superblocks. Fdisk doesnt show mdraid superblocks, too.
But fdisk has never showed superblocks.

The thing is, this raid was crypted, but i crypted the /dev/md0, so this doesn't affect anything here, or?

some infos:


server:~# mdadm --misc -d /dev/sda
mdadm: option -d not valid in misc mode
server:~# mdadm --misc -t /dev/sda
mdadm: /dev/sda does not appear to be an md device
server:~# mdadm --misc -t /dev/sdb
mdadm: /dev/sdb does not appear to be an md device
server:~# mdadm --misc -t /dev/sdc
mdadm: /dev/sdc does not appear to be an md device



server:~# mdadm --assemble --scan -v
mdadm: looking for devices for further assembly
mdadm: cannot open device /dev/dm-2: Device or resource busy
mdadm: cannot open device /dev/dm-1: Device or resource busy
mdadm: cannot open device /dev/dm-0: Device or resource busy
mdadm: cannot open device /dev/sdd2: Device or resource busy
mdadm: cannot open device /dev/sdd1: Device or resource busy
mdadm: cannot open device /dev/sdd: Device or resource busy
mdadm: no recogniseable superblock on /dev/sdc
mdadm: no recogniseable superblock on /dev/sdb
mdadm: no recogniseable superblock on /dev/sda
mdadm: No arrays found in config file or automatically



Disk /dev/sda: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xc703d08e

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

Disk /dev/sdb: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xd49fed3e

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

Disk /dev/sdc: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x1b9e3db0

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


But fdisk always said there is no valid partition table and the raid was working.

Does anybody have an idea?

Thanks!!

deadball
April 15th, 2010, 06:00 PM
No ideas? :)

Cracauer
April 15th, 2010, 11:21 PM
My first guess is that you were on partitions (sda1 etc) and now specified disks (sda with no partition digit). Possible?

Do you have any kind of /proc/mdstat output from when the old array was running?

A hexdump of the beginning of the disk might show where the heck the md superblock actually is.

deadball
April 16th, 2010, 05:21 PM
Hexdump is a nice idea. How does the block look like?

No, i did not create any partition.

And i think i dont have a output, but i will search in my old logfiles! thx

deadball
April 19th, 2010, 05:58 PM
Recreating via mdadm --create raid-level=5 raid-devices=4 missing /dev/sda /dev/sdb /dev/sdc

did it :)