Answers:
For earlier version, IP-guard uses the volume ID as the criteria to identify the USB disk.
Volume ID is the identifier.
For new IP-guard version, there is a new criterion named Udisk ID.
It is the hardware value for the device.
IP-guard introduces this new criterion to handle some complicate case.
IF client upgrade from earlier version of IP-guard, by default there is a value setting in Operation->Matching rule… inside the Removable Storage categories.
#1, Value="Only Volume ID"
Please do NOT delete this setting.
With this setting, IP-guard still uses volume ID as the identifier.
If you delete this setting, IP-guard will use the new Udisk ID as the identifier.
After deleting this value, the process is not reversible.
For existing client who use any removable policy, the client need to keep using Volume ID.
Otherwise their existing policy may contain problem.