[SATLUG] RAID5 Recovery - ddrescue: 2nd round

Samuel Leon satlug at net153.net
Sun Aug 23 17:13:21 CDT 2009


I will have to step out soon and won't be back until 9pm. If you are 
confident that all of your data was properly copied then reconnect 
everything and bring the computer up.  Might also make sure that all 
your disks are linked to the right device names as needed (sda,sdb ect)

Then make sure that sdc atleast has the raid superblock on it:
mdadm --examine /dev/sdc
If that brings back what looks like a raid drive then we should be good 
(you could probably actually do that before you reconnect all of the 
other drives)

then force the array to reassemble:
mdadm --assemble --force /dev/md0 /dev/sde1 /dev/sda1 /dev/sdb1 /dev/sdc1

(make sure those drive numbers are right, I copied them from an earlier 
post. Also, if you don't get some output saying that the array has been 
started then you need to stop right here.  The output you should get 
should be similar to:
mdadm: forcing event count in /dev/hdd1(2) from 228 upto 232
mdadm: clearing FAULTY flag for device 1 in /dev/md0 for /dev/hdd1
mdadm: /dev/md0 has been started with 2 drives (out of 3).
)

That should bring it up in degraded mode with one failed drive. So then do:
mdadm -D /dev/md0

and that will list some info and at the bottom you will see what drive 
is still removed.  So add it to the array with:

mdadm --add /dev/md0 /dev/sdX

but if there is still more than one drive missing from the array at this 
point never use mdadm --add because something is wrong and that will 
make it worse.

If added correctly, the array should start to resync.  Let it finish and 
then and make sure the filesystem on /dev/md0 stays unmounted.  Once it 
is done resyncing check the filesystem (if it is ext3) with:
e2fsck -D -f /dev/md0

You will probably get some errors and have to press "y" a hundred times. 
Any files that are lost will be put in your lost+found folder and will 
be given their inode number as the file name.

Then you should be done.

Sam


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