[CentOS] mount: /dev/sdb1 already mounted or /blah busy

Wed Apr 23 09:43:13 UTC 2008
James Pearson <james-p at moving-picture.com>

Al Sparks wrote:
> How do I go about troubeshooting this?  I'm using RHEL 4 update 6.
>    mount: /dev/sdb1 already mounted or /blah busy
> It's actually an iSCSI LUN (NetApp filer).  I successfully configured (ext3) and mounted it, but when I rebooted, the /dev/sdb1 device/partition is seen by the kernel and it shows up with "fdisk -l".
> Nevertheless I get that error.  I've tried "umount" and am informed that /blah isn't mounted.  I've tried "lsof" and don't find a process that's attached to /blah.
> I also tried "fsck -t ext3 /dev/sdb1" which worked (so it detects the ext3 file system).
> Any other tools to check out?

Do you have an entry for /dev/sdb1 in /etc/mtab ? If so, try manually 
removing that line and try the mount again.

James Pearson