Hello, I just wanted to document in this thread the commands and steps I followed with Robin's help after having a second drive fail during the synching of a RAID5 array. - First step I did was take a picture of my error on screen. And save a copy of the output of mdadm -E /dev/sd[abcd]3 and mdadm --detail --scan /dev/md0. and smartctl -a /dev/sda #for each drives since it was nice to have the serial numbers match up with each UUID device mdadm -E gave. - Second step I did was to boot with a liveusb and use ddrescue to clone 3 of my 4 drives. The first drive that failed was totally malfunctioning, but I was able to ddrescue my 3 other drives. I booted with ubuntu's rescue remix live usb distro and ddrescued each drive one at a time with a new drives I purchased. ddrescue -f -n /dev/sda /dev/sdb /mnt/sdc2/ddrescue.sda.log ddrescue -f -r3 /dev/sda /dev/sdb /mnt/sdc2/ddrescue.sda.log - After the cloning process was done, I booted again with only the new cloned drives. I ran mdadm -E /dev/sd[abc]3 | grep "UUID Dev" and compared that output to the one I took original when everything first failed. This was important since the ordering of my drives did not match anymore. After figuring out the correct order I ran thing command that Robin helped me sort out. mdadm -v --create --assume-clean --level=5 --chunk=512 --size=1952795136 --raid-devices=4 /dev/md0 /dev/sdd3 /dev/sdb3 /dev/sdc3 missing - At this point I was able to run fsck -n /dev/md0 which told me my ext4 partition was clean. >From this point on you have 2 options. mount in read-only and backup, or insert a new drive to add to your array. I went the safe way and mounted in read-only: mount -o ro,noload /dev/md0 /mnt rsync -axvSH /mnt/ /mnt2/ - The final step for me was to add a new fourth drive to my degraded raid5 array. mdadm --add /dev/md0 /dev/sda3 A cat /proc/mdstat confirmed the resynching process. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
