I've recently built a new system, after a rather large physical injury was sustained by my previous system (a precarious balance, and gravity, were not a happy mix). Surprisingly the /home drive of that system appears to have more-or-less survived the trauma. However...

I decided to use a fresh drive for / (and swap) partition(s), and another fresh drive for the new /home. Now that's working, I decided to install the old /home drive (that I had assumed until now would be entirely dead and without capacity for use) into the new system to recover the files and data (so far as is possible).

At this point I've run into a snag: I have no idea how to go about this (with Windows it was relatively easy, the new drive would be the latest character of the alphabet, and go from there).

With 'disk utility' (System -> Administration -> Disk Utitlity) I've worked out which drive it is (/dev/sda) but clicking on 'mount' produces an error:

1: helper failed with:

mount: according to mtab, /dev/sdb1 is already mounted on /

mount failed

...if it is mounted on / I can't see it. I'm also moderately confused by the disk (device /dev/sda) being referred to as /dev/sdb1.

Any and all insights would be incredibly welcome (I've already voted for: Idea #9063: New internal hard drives default automount at Brainstorm).

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Edited in response to Roland's request for a screenshot of disk utility:

Details (so far as I know them):

1. 40GB disk is / and swap,
2. 1.0 TB Samsung is /home
3. 1.0 TB Hitachi is from the old system (and was the old /home drive).

Output from sudo fdisk -l pasted below:

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 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: 0x000bef00

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1      121601   976760001   83  Linux

Disk /dev/sdb: 40.0 GB, 40018599936 bytes
255 heads, 63 sectors/track, 4865 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: 0x00037652

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        4742    38084608   83  Linux
/dev/sdb2            4742        4866      993281    5  Extended
/dev/sdb5            4742        4866      993280   82  Linux swap / Solaris

Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 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: 0x000e8d46

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1      121602   976760832   83  Linux