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Full Version: How To Move A Raid Array Between Systems
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Graeven
ok...so last week I had a power failure while I was away and before I could get back the USP ran dead so the system died (yes i know....use the shutdown script...Im workig on it). On reboot the drive with / and /boot and stuff died so I had to replace it. The raid arrays seem fine but I'm unsure how to get them back in the system on a fresh RH9 install without losing all the data on them. I've read lots of documents and still can't find anything to help me. I can't find a raidtab file nor a mdtab file in /etc or anywhere else.

When I run cat /proc/mdstat I get this:

Personalities : [raid0]
read_ahead 1024 sectors
md1 : active raid0 hdf1[0] hdh1[1]
241247872 blocks 64k chunks

md0 : active raid0 hde1[0] hdg1[1]
241247872 blocks 64k chunks

I can mount both md0 and md1 but I can't read any information on them. I've run fsck and it reports them both as clean.

I'm really at a loss of what to do now and any help would be greatly appreciated.


Graeven
hughesjr
You need to either have (or recreate) the raidtab file that defined your array (exactly as it was) ... otherwise you will lose all the data on the drives.
Graeven
Thanks for the info. I was able to recover the riadtab file from the bad drive and have it in the right place. some steps from there would really be greatly appreciated.


Thanks again

Graeven
hughesjr
OK ... since you are booting from a seperate drive, you should be able to put the new raidtab file in /etc.

When you mount /dev/md0 it should have all the info still there ... if it doesn't, it is probably not available any more.

Did you do anything (like mkraid /dev/md0) after the original problem?
Graeven
I havent done anything with the raid drives other than try to mount them since the first problem. I can mount them as I could before i had the raidtab file but I get the same results. After I mount them and run ls all I get get a mess of jumbled garbage. All the listings are similar to ???z7=?.??j

Does this mean all my data is lost? Does just adding the raidtab file back in fix this? I read somewhere about having to resynch the drives with mdadd --force so the superblocks were correct but I cant find that site again and am not sure what was done.
hughesjr
Take a look here for info concerning mdadm.

All I had to do when moving 3 drive Software RAID to a new PC was to moave the /etc/raidtab file to the new machine and hookup the drives in the correct order...

Specifically, look at section 8.1 ... I think the command you are looking for is:

mdadm --assemble --force
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