RAID 5 won't mount
I have a RAID5 array with 3 WD RED disks (sdb, sdc sdd), where one drive gave up. I replaced the drive and rebuild. Now the array won't mount.
My mdadm conf: Code:
# mdadm.conf# Code:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]md0 : active raid5 sdd[2] sdc[0] sdb[3] Code:
fsck from util-linux 2.20.1e2fsck 1.42.9 (4-Feb-2014) Code:
/dev/sdb: Code:
mount: wrong fs type, bad option, bad superblock on /dev/md0, Code:
[ 85.150872] EXT4-fs (md0): Couldn't mount because of unsupported optional features (1fd00001) |
You might want to try Testdisk to see if it finds a filesystem. If not try Photorec which will scan for your data based on file extension.
Further action, if needed, will depend on the results you get. |
And did you try the fsck with the alternate superblock(s) as the message told you ?.
|
Personal take
I would work on that for about an hour, then just rebuild the array blank, and restore from backup.
You DO have a backup, yes? Actually, being somewhat adventuresome, I might rebuild using btrfs with some of the raid features turned on. |
I will try #2 and #3
Unfortunately my backup system didn't include the RAID array ;-( Lesson learned, the hard way. |
Nor should it - the array is at the (emulated) device level. You seem to have reconstructed that ok. For the superblock problem, if fsck won't fix it, do a mkfs and restore your data. Tools like photorec are for people that don't have backups - it scans the disk looking for tell-tale signs of files. Sometimes works, sometimes not. And what is the level of confidence ?.
As for @wpeckham comments on btrfs RAID, no better in some respects - I use it (RAID5) for my important data, but you still need backups. Differential snaps are a boon, but for RAID[56] device replacement you need to be reasonably current on kernel and btrfs-progs (say Feb 2015). Still the best solution IMHO. |
Backups
I have been a professional SYSADMIN for over 20 years, a NETADMIN for half that.
If I have learned one thing, it is that you can be good or bad at almost any part of this business and succeed ONLY if you are good at backup and recovery. We wear a dozen hats, and it is good to be excellent at many or all of our jobs, but this is the ONE thing that is survival: for the businesses we support and for our career. If you are not a professional, it is less of a priority, but still a good lesson. Every newbie must suffer through learning this at some point: no system/hardware lasts forever. My first rules of backups (not my invention, any experienced sysadmin might list the same): 1. Don't back up everything, only back up what you do not want to lose. 2. No storage solution takes the place of backups. Notice that is plural: if one failure can kill it, one is not secure. 3. It cannot be called a good backup, until restore is tested. I hope that you can recover your data, and wish you the best of luck! |
@syg00, To clarify
Quote:
As for Photorec one reason to run it here is as a test to validate the RAID is assembled correctly. If for example Photorec recovers a 2MB .jpg file that renders fine then chances are the RAID is in good shape. For the best chance of recovery the rule is to avoid any operation that writes to the RAID member drives, including fsck. If this is high value data for maximum safety it is best to take drive images and perform recovery work on the images. |
Quote:
My mistake. Quote:
|
Thanks for all the answers. I will get a hold of some drives and make drive images and try the suggestions.
|
All times are GMT -5. The time now is 09:00 AM. |