WE are setting up a new backup env with nw 8.1 and dd.  we will be backing up unix , windows and vmware guests (using vba). Does it make sense if  I create 3 devices and 3 media pools , so that device1 backups only unix, device2 backups only wiindows and device3 only vmware?

since our old seup is with nw 7 and lto tapes , I try to make the new seup  configured similar to the old one.  May be that  is not right when using dd. 

we will be backing up nearly 200 physical and 200 vmware guests.  How many devices should I create for better perfomance?

unlike tape drives which can mount different volumes, a dd device mounts only 1 volume and use it forever, is that right?

Thanks

james