Datavolume doesn't exist ! message

[Cohiba88]

Thanks Fibreiv! I know what happened to my worldspace which caused teh problem, since it has happened for the second time. The POWER was shut down, due the the UPS running dry WHILE it was consistency checking from a previous power outage. The consistency check usually takes 8++ hours. I managed to get my data back. The trick was to figure out which drives to assemble. Out of 4 drives a b c d, it seemed that 2 of them were not working. But when I checked drive sde4, the drive was fine! So I assume that what happened is that when the unit rebooted, it tried to assemble a RAID5 using drives sda4 sdb4 sdc4 sdd4, and 2 were not working. I manually created a raid5 using a b c e and it accepted it using the commands you provided. Here are some of the commands I used to see the status mdadm --detail /dev/md[0123] when it did not allow me to add e drive mdadm --assemble --force status messages mdadm --monitor more investigation messages mdadm --examine /dev/sd[abcde]4 stop the raid mdm -S /dev/md0 start raid mdm -R /dev/md0 see status cat /proc/mdstat more status, which is like what you will see int eh web interface tail -f /var/log/messages I wish WD would somehow update their software to be able to recover from these issues, since the data was acutally not damaged. And there are a lot of people getting this error and losing their data. – although not the complete process, here is a capture of the last moments of recovery. Note that the lvmr figure had to be changed from what fibreiv wrote. When it worked, it was tears of joy!!! dev $ pvcreate /dev/md2 No physical volume label read from /dev/md2 Physical volume “/dev/md2” successfully created /dev $ vgcreate lvmr /dev/md2 Volume group “lvmr” successfully created /dev $ lvcreate -l 714329 lvmr -n lvm0 Insufficient free extents (714218) in volume group lvmr: 714329 required /dev $ lvcreate -l 714218 lvmr -n lvm0 Logical volume “lvm0” created /dev $ **bleep**.ext **bleep**.ext2 **bleep**.ext3 /dev $ **bleep**.ext3 /dev/lvmr/lvm0 e2fsck 1.38 (30-Jun-2005) Couldn’t find ext2 superblock, trying backup blocks… ext3 recovery flag is clear, but journal has data. Recovery flag not set in backup superblock, so running journal anyway. NASRAID: recovering journal