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I am trying to configure ShadowProtect SBS (v. in Windows Server 2003 SBS to backup my server hard drives to two alternating external drives. What I want is to be able to swap one drive for another every Friday, and have ShadowProtect continue on the same schedule. Ideally, this would require absolutely no user interaction whatsoever, apart from physically unplugging one drive and reconnecting the other.

The trouble is, Windows Server 2003 does not allow you to assign the same drive letter to two different devices. So if I plug in drive #1 and assign it drive letter "X:", the next week when I unplug it and plug in drive #2, it gets some other letter. But since ShadowProtect is set to backup to "X:\", it can't find it and the backup fails. The drives are Samsung STORY Station 3.0 2TB drives.

How can I configure things so I can just swap the drives over every week and not worry about having to reconfigure drive letters every time?

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up vote 1 down vote accepted

I used the USB Drive Letter Manager utility by Uwe Sieber — it's a service that can assign drive letters to USB drives based on IDs, name, brand, etc. In my case, I configured it with:

DeviceID1=USBSTOR\DISK&[rest of id for first drive goes here]
DeviceID2=USBSTOR\DISK&[rest of id for second drive goes here]

The IDs were found with the ListUsbDrives.exe utility that comes with it.

(Found via this answer to How to make sure that an external USB drive gets the same drive letter.)

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Windows Server 2003 does allow you to use the same drive letter for two different drives, but not with both connected at the same time. I've done this exact thing.

  1. Give one drive the drive letter that you want.
  2. Disconnect it.
  3. Connect the other drive.
  4. Give it the same drive letter.

Each drive will now have the same drive letter and problems will only arise if you connect both drives at the same time. I've had to hack backup scripts that relied on this ability of Windows. It's not pretty, but it'll do.

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No, I tried this. When I assign the letter "X" to the second drive, disconnect it, and plug in the first, it gets assigned the letter "F". I believe it has something to do with the fact the the registry entires used for this have the drive letters for keys, and thus can't be duplicates. – detly Apr 3 '12 at 3:48
This is using "Computer Management > Disk Management", right click on the volume and select "Change Drive Letter and Paths..." – detly Apr 3 '12 at 3:50
You're doing exactly what I've done, and yet our results are different. As of yet, I have no explanation for that. – Wesley Apr 3 '12 at 3:51
I think "aliens" is the most plausible explanation. The registry keys I'm talking about are under HKEY_LOCAL_MACHINE > SYSTEM > MountedDevices. The relevant entry is (name, type, data) = (\DosDevices\X:, REG_BINARY, [some binary data, probably UUID?]). – detly Apr 3 '12 at 4:36
If you're interested, I found a utility that does this quite nicely (see my answer for details). – detly Apr 27 '12 at 0:29

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