<snip>
[root@k5di ~]# mount -t ext2 /dev/sdb5 /mnt
mount: /dev/sdb5 already mounted or /mnt busy
The last 2 lines say that /dev/sdb5 is mounted to this Old Hard Drive
somehow.
<snip>
Karl F. Larsen, AKA K5DI
No, the last two lines is
telling you that either
/dev/sdb5 is already mounted
OR
the mount point /mnt is busy
Which is not to be confused with meaning something is already mounted
there. You can mount something on top of a currently mounted device
(and repeat if you wish). You will not see the underlying mounted
device mounted at that mount point until after you unmount the last
mounted device (and continue unmounting in reverse order everything
mounted at that mount point). So if the second scenario is applicable
then something else is going on causing /mnt to be busy hence refusing
to mount /dev/sdb5 at that mount point.
As was suggested, type mount with no other options to see what is
mounted (keeping it simple - there is a caveat that most likely does
not apply so I won't go there and further confuse things).
Jacques B.