Because not enough information exists in easy-to-find searches: as a simple reminder – SCSI device IDs can and will change.
A few months ago I hot-added a new disk to an ssh bastion host (a VM on ESX). As these things tend to go, I eventually took a maintenance window and updated firmware/BIOS/OS on the ESX host. When the bastion VM came back online, however, I was presented with an odd error:
[root@bastion ~]: fsck /dev/sdc1
e2fsck 1.39 (29-May-2006)
fsck.ext3: Device or resource busy while trying to open /dev/sdc1
Filesystem mounted or opened exclusively by another program?
[root@oracle1 ~]# cat /proc/mounts
rootfs / rootfs rw 0 0
/dev/root / ext3 rw,data=ordered 0 0
/dev /dev tmpfs rw 0 0
/proc /proc proc rw 0 0
none /selinux selinuxfs rw 0 0
devpts /dev/pts devpts rw 0 0
tmpfs /dev/shm tmpfs rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw 0 0
[root@oracle1 ~]# cat /etc/fstab
/dev/main/root / ext3 defaults 1 1
/dev/sdc1 /home ext3 defaults 1 2
/dev/main/var /var ext3 defaults 1 2
/dev/main/tmp /tmp ext3 defaults 1 2
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/main/swap swap swap defaults 0 0
# Beginning of the block added by the VMware software
.host:/ /mnt/hgfs vmhgfs defaults,ttl=5 0 0
# End of the block added by the VMware software
So everything in the fstab is how I left it – /dev/sdc1 is the new disk I added that is giving errors mounting. So I thought to check for corruption on the disk, and found the problem:
[root@oracle1 ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 5221 41833260 8e Linux LVM
Disk /dev/sdb: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 5221 41937651 83 Linux
Disk /dev/sdc: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 * 1 3917 31457279+ 8e Linux LVM
So, a simple fix – change “/dev/sdc1″ to “/dev/sdb1″ in /etc/fstab (or to VOLUME=home), and boot back up.
It’s not something that’ll probably happen on this server again, but it is something to be aware of, on both VM guests and on physical servers. This is why so many newer Linux OSes are using UUID= or VOLUME= instead of device path for SCSI disks.