Windows Drive Letters - Can be set to always use same letter on mount


#1

Hi - another Ex-Crashplan user here migrating to Duplicati. Thanks for producing a good looking alternative.

Can I help with a bit of hidden knowledge. I have an answer to one of your Help Issues

It is possible to fix the drive letter for any hard drive in Windows. USB drives, flash drives, fixed internal disks. Trick works with all of them.

  • Plug your drive in
  • Start Disk Management ( Win+R then type discmgmt.msc )
  • Right click your selected disk and select “Change Drive Letter and Paths
  • Press [Change] and choose a new letter.

You will now find that everytime you plug this drive in in future it will always be given this letter (if it is free).

I can make some screenshots to show this if required. Just seems the current “solution” in the FAQ is going a long way round to solve something simple (if undocumented). :slight_smile:


#2

You can also use the wildcard driver letter in a source folder to backup a folder on any drive (e.g., *:\Pictures will backup C:\Pictures, D:\Pictures, E:\Pictures, …

Or, you can specify the drive by its unique volume id (which can either be found via the mountvol command, or picked from the list displayed by Duplicati.CommandLine.exe help backup) as \\?\{volume id}\Pictures.


#3

Hi @BatterPudding, welcome to the forum and thanks for sharing your info!

Do you happen to know what happens if it’s not free - does the drive not mount or does it get assigned a different letter?

For what it’s worth, I ran into a similar “mount point” issue on MacOS where if the USB drive wasn’t mounted a folder with the name of the USB drive was created thus causing all future runs to fail because all data was missing - even after he USB drive was attached! I ended up using the --alternate-destination-marker solution from the above link to get things working correctly.


While being kinda cool, this sounds like a potential recipe for disaster with removable drives. Let’s say you’ve got two removable drives both with ?:\Pictures folders and they mount as drive 1 = E:\Pictures and drive 2 = F:\Pictures each with different pictures.

When the backup first runs you’ll get a nice backup of E: and F: pictures folders. But if the drives are then mounted such that now drive * 2 * = E:\Pictures and drive * 1 * = F:\Pictures and another backup is run I expect Duplicati will consider each folder to have a ton of deletes and adds.

Granted, the deduplication shouldn’t cause a whole lot of re-uploading, but when it comes time to restore files it might get confusing exactly what is being restored…


#4

The drive always mounts.

When you go to choose a letter the list only shows those available at that time. So you should be able to set it as unique. Make sure you set it to something at the far end of the alphabet. Or use the A and B of the old floppy drives as these are never handed out by Windows.

If you allocate “S” to your external drive it will keep being “S” when you plug it in.

If you allocate “S” to second external drive, then Windows forgets about the first and that will go back to being automatic.

If you manage to plug in 17 drives then Windows will auto-allocate the letter “S” and forget about your external drive. Next time the external drive is plugged in it will be the “next free letter” again.

I have just experimented with some flash drives to get the exact rules of the above. As I’ve always used R,S,T,U,V for my external drives an X for my DVD-RW I had never noticed the reallocation happening.

In reality this is very easy to keep track of. Just write the drive letters on the external drive.

@tygill I agree with your summary of the wildcard backup. I have way too many different drives to risk that method. Though I can see how it would work in a more “normal” computer. Especially with camera folders in \DCIM\

I like the very technical solution supplied as it is bullet proof. But a bit geeky for those who like GUIs.