Mikko Tunturinen - 2020-01-03

I have a GPT partition which is encrypted with the same password as my system partition. I'm trying to add this partition as a System Favorite Volume so that I can avoid the manual work of mounting it every time I start Windows. I'm getting the following popup:

The volume you are adding to favorites is a partition not recognized by Windows.

VeraCrypt will be unable to mount this favorite volume if the device number changes. Please set the type of the partition to a type recognized by Windows (use the SETID command of the Windows 'diskpart' tool). Then add the partition to favorites again.

From the description it sounds like a warning, not an error. It sounds like VeraCrypt should be able to mount the volume automatically as long as the device number doesn't change. However, that doesn't appear to be true (the volume is not mounted if I shutdown and boot up again). I also tried to select "Use Volume ID to mount favorite", thinking that the volume ID is not going to change even if disks spin up in different order or whatever. This didn't work either.

Next I tried to follow the instructions in the warning and set a different GUID for the partition, but the instructions don't say which GUID is expected. The Wikipedia entry for Partition type GUIDs lists a hundred different options, each with various, unknown and undocumented implications. I tried a few of them:

Setting the partition GUID to Linux Reserved 8DA63339-0007-60C0-C436-083AC8230908

...doesn't do anything, the same VeraCrypt message appears.

Setting the partition GUID to Windows Basic Data Partition EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

...makes the VeraCrypt warning/error message disappear, so presumably this GUID would allow me automount it as a system favorite. However, setting this GUID caused Windows to immediately mount the partition with a recommendation that I format the partition. I know I can prevent this from happening in the future by disabling the drive letter, but a Windows feature update is going to reset drive letters and pop up the format dialog again. I dont' want to accidentally hit enter on a format dialog and lose data when this happens. In addition, I'm afraid that a Windows update/repair/whatever might autoformat a partition which is marked as Windows Basic data partition and appears as unformatted to Windows. Due to these reasons I do not want to use Windows Basic Data Partition GUID for this partition.

There are many more GUIDs I could try, but without understanding the implications of what I'm doing, it doesn't make sense to blindly try to set them.

So my question is: how can I safely automount partitions at Windows startup?

 

Last edit: Mikko Tunturinen 2020-01-03