I added a 2TB drive to my system (NOT to my RAID 5 array, just an additional single drive), and now the array won't mount - I get a "mount: /dev/md0 already mounted or /media/storage busy" error. Everything's worked fine for 2 years. All I did was successfully update the MB bios, attach the 2TB Samsung hard drive, formatted it ext4 with a 1MB offset using a gparted bootable CD, then restarted my regular Ubuntu 9.10 system, at which point the array doesn't mount and I get the "mount: /dev/md0 already mounted or /media/storage busy" error.
mdadm says everything's still fine:
mdadm --detail /dev/md0 /dev/md0: Version : 00.90 Creation Time : Sat Aug 2 16:39:27 2008 Raid Level : raid5 Array Size : 2197715712 (2095.91 GiB 2250.46 GB) Used Dev Size : 732571904 (698.64 GiB 750.15 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 0 Persistence : Superblock is persistent
Update Time : Sat Nov 6 08:17:54 2010 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K UUID : 59d14b52:c05d4166:1246e5fe:589d0142 Events : 0.3735628 Number Major Minor RaidDevice State 0 8 17 0 active sync /dev/sdb1 1 8 33 1 active sync /dev/sdc1 2 8 49 2 active sync /dev/sdd1 3 8 1 3 active sync /dev/sda1
scan looks fine too:
mdadm --detail --scan ARRAY /dev/md0 level=raid5 num-devices=4 metadata=00.90 UUID=59d14b52:c05d4166:1246e5fe:589d0142
But I can't mount it:
mount /media/storage mount: /dev/md0 already mounted or /media/storage busy
mdadm.conf still seems correct and matches scan output (and worked fine for 2 years until now):
# mdadm.conf # by default, scan all partitions (/proc/partitions) for MD superblocks. # alternatively, specify devices to scan, using wildcards if desired. DEVICE /dev/sd* # auto-create devices with Debian standard permissions CREATE owner=root group=disk mode=0660 auto=yes # automatically tag new arrays as belonging to the local system HOMEHOST <system> # definitions of existing MD arrays ARRAY /dev/md0 level=raid5 num-devices=4 UUID=59d14b52:c05d4166:1246e5fe:589d0142
...and fstab looks correct (and has worked for 2 years as well):
# /etc/fstab: static file system information. # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 # / UUID=4204d07b-c450-4461-a001-1ef6d4ecb1a3 / ext4 errors=remount-ro 0 1 # swap UUID=95331961-9abd-4795-9443-292146aca413 none swap sw 0 0 # RAID storage drive /dev/md0 /media/storage ext3 auto,rw,user,relatime,noatime,nodiratime,exec,async 0 3
I'm at a loss for what to try next...