Save Lono

I recently upgraded to Fedora 13(and was quite pleased) only to discover my backup SATA drive would not mount.  I got the generic, ‘mount: /dev/sdb1 already mounted or /home/matt/backup busy’ error message.  Hours of googling and one reinstall later I solved the problem.

Goals of this Post:

– Fix SATA drive mount error: mount: /dev/sdb1 already mounted or /home/matt/backup busy

I did a clean install, but before hand I copied all my important data to my backup disk.  I was disappointed because recently I had to deal with several driver issues in the Window 7 installation process… and now Linux…  

I tried to mount my FAT32 partition to recover my old files, but kept getting this error: mount error: “mount: /dev/sdb1 already mounted or /home/matt/backup busy”.

This is a fairly common error message.  You will see this message as a ‘evms(Enterprise Volume Management System) bug’ in Unbuntu or if you don’t have the module for said file system(like NTFS, FAT, ext4, etc…). I spent several hours wrestling with this issue before I discovered the culprit.

[root@mattcom ~]# mount -t vfat /dev/sdb1 /home/matt/backup
mount: /dev/sdb1 already mounted or /home/matt/backup busy

So I checked to that if the disk was mounted,

[root@mattcom ~]# df -H
Filesystem             Size   Used  Avail Use% Mounted on
/dev/sda2               72G   4.1G    64G   7% /
tmpfs                  1.8G   709k   1.8G   1% /dev/shm
/dev/sda1              204M    24M   170M  13% /boot
[root@mattcom ~]#

The disk was not mounted, so I checked fdisk…

[root@mattcom ~]# fdisk -l



Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000112e6



Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26        8822    70656000   83  Linux
/dev/sda3            8822        9730     7288832   82  Linux swap / Solaris



Disk /dev/sdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0002b779



Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       19457   156288321    c  W95 FAT32 (LBA)

My partition was there as expected.  So I decided to check my boot.log just in case I had missed something.

[root@mattcom ~]# cat /var/log/boot.log
Welcome to Fedora
Press ‘I’ to enter interactive startup.
Starting udev:                                             [  OK  ]
Setting hostname mattcom:                                  [  OK  ]
Setting up Logical Volume Management:   /dev/md126: read failed after 0 of 4096 at 0: Input/output error
No volume groups found  [  OK  ]
Checking filesystems
/dev/sda2: clean, 122201/4423680 files, 1158068/17664000 blocks
/dev/sda1: clean, 36/51200 files, 29315/204800 blocks   [  OK  ]

My boot log showed a ‘Input/output error’ on ‘/dev/md126’. I read a post in my googling that suggested the ‘fsarchiver’ tool.  It also showed the mysterious ‘/dev/md126’.

I thought it was possible that Linux was thinking my SATA drive was part of a RAID array.  So I used the ‘mdadm’ tool to check.

[root@mattcom ~]# cat /proc/mdstat
Personalities :
md126 : inactive sdb[0]
156288642 blocks super external:/md127/0



md127 : inactive sdb[0](S)
2257 blocks super external:imsm



unused devices: <none>

[root@mattcom ~]# mdadm –stop /dev/md126
[root@mattcom ~]# mdadm –stop /dev/md127

[root@mattcom ~]# mount -t vfat /dev/sdb1 /home/matt/backup
[root@mattcom ~]#

Success!  Once I stopped the RAID devices /dev/sdb1 was mount

By now I was convinced that that the dmraid driver had flagged my disk as part of a RAID array

I found the answer at the mdadm WIKI page, http://en.wikipedia.org/wiki/Mdadm

mdadm –zero-superblock /dev/sdb

Now everything boots fine and the hard drive can mount normally!  I hope this article helps someone else.