You would have to move the whole of the Arcserve directory onto another volume. But in doing this, you would also have to amend all of the configuration files to point to the new location.
So, the way I see it is that you have four choices:
1. Move the Arcserve Directory to another volume and spend the rest of your living days amending the INI files and NCF files
2. Reinstall Arcserve onto another volume (and move the database over as well)
3. Purge the Arcserve database using the Arcserve Manager to set parameters to purge
4. Stop Arcserve (ASTOP6 on the server) and copy the contents of EMPTYDB into the DATABASE directory (overwriting) and start Arcserve (ASTART6). This will mean your Arcserve database will be blank "It's true, its damn true!"