I've got a friend with a 1tb raid10 and 2 separate hot swappable 1tb drives runnin win7 ultimate.
I created a scheduled task that would create a system image backup of the main raid array to the 1tb drive. I setup the task, and tested it with the first drive and it worked as expected.
The idea is that the whole system is backed up such that if the raid array suffers catastrophy (ie. house fire) then he can toss the drive into another machine, startup and be good able to access all of his information.
Now, after the backup is done once a week, he takes the drive, tosses it in a fire proof safe, and takes the second 1tb drive out of he safe and throws it in the machine.
I asked to be sure and the second drive is assigned the same drive letter, so the backup should run as expected. But I'm hearing that it doesn't. I haven't taken a look at the system yet, so I don't know a whole lot more outside of that but is there anything that anyone can think of that would cause any backups to fail in this situation?
If there is a mapped drive taking up the previously assigned drive letter, then the newly/re-on-line drive will sit in "idle" with no drive letter assigned. It will stay in that "state" until a different drive letter is manually assigned or the mapped drive is brought off-line and the physical drive is physically cycled (swapped or disconnected & reconnected) back into the system to assume its previous drive letter assignment (which will now be available with the mapped drive off-line).
I think what you really need to do is, sigh, script this. As @user48838 points out, you will have a problem if you assign the same drive letter. The only way I can envision effectively using the same mount for two different volumes is to script to check the volume's GUID. Then, make the sure other volume is not mounted by checking its GUID. If not, proceed to mount it with the mountvol utility. I would imagine this is possible with batch, VBScript, or PowerShell. To get an idea of what I am talking about, see the documentation for the utility here. If you like the idea, I can try to whip up a script when I have some more free time.