We plan to start with DST next time and there are some questions open:

The 1. step is to migrate an existing Volume which consists of multiple
partitons (LUN's) to a new Volume on one new LUN.
Can i change the volume role if i create the new volume as a shadow
volume first and create a policy to move all data? Than i want to change
the shadow volume to primary and create a new shadow volume on
inexpensive storage.

Are there any issues with home directories ?

How does a backup system handle DST ? In our case Simpana connects to
NSS as a eDirectory user which means it has the same view to the file
system like a user. How can i split primary and shadow volume jobs ?