Are you planning to switch from DSM6 bare metal to DSM7 VMs?
You don't usually do this well, do you?
Migration from bare metal to bare metal and from VM to VM seems safe.
The most critical problem in the migration from DSM6 -> DSM7 is
The point is that setting up SataPortMap is not easy, especially in REDPILL.
Of course, there are users who are lucky enough to pass easily.
The recommended method is to remove all data disks in use from the XPE PC and install only a few new disks for testing.
Install and prepare the existing DSM 6 first,
After creating one more REDPILL DSM7 bootloader on a separate USB,
The first thing to do is to test the migration.
If there are no problems in this test, it is OK to migrate the real data disk.
Unless you intentionally initialize the disk,
In any case, there is no need to worry as the data partition area is not damaged.