Hello,
General thought :
You don't need to create a new backup device. You only have to add another gateway.
As you do not delete your store ... you can "connect" a new device to an existing store (but one store can only be used by a device at a given time)
Now more precisely.
Before modifying anything ... the setup I'll explain you have some drawbacks.
Your cell Manager at the DR site can not launch any backup unless you promote it again as a cell manager. So if you are make some backups at your DR site ... you won't be able to do them anymore.
For the example, CS-A = production Cell Manager ; CS-B=DR Cell Manager
You must install at least the DA, MA, StoreOnce Software (SOS) , CS and CC on both servers (I assume that it is the case)
Stop all DP services but the omniinet and the SOS on the standby CS.
Modify the HKEY_LOCAL_MACHINE\SOFTWARE\Hewlett-Packard\OpenView\OmniBackII\Site\Cell Server key on the Standby CS and write the fqdn of the production CS.
Import your standby server on the production Cell
Now you Standby CS is a simple client of your production CS
Let's start the storeonce configuration
Modify your running storeoncedevice and add the CS-B as a server-side gateway on it (optionnal but can be useful if you want to continue the same scenario in case of a running DR and of course the site A operationnal ^^)
Add another storeonce device with the CS-B as the storeoncesoftware dedupe system. The first gateway will be CS-B.
Add to the new storeonce device the CS-A as a server-side gateway.
Now perform an object copy between the production B2D device and the second gateway of the new B2D device.
The first copy will take a lot of time because of (rehydratation + store population) but any subsequent transfert should be faster because the store will be populated.
Off course it depend of your WAN speed and the redhydration that is mandatory with storeonce software (but not with storeonce appliant + StoreOnce catalyst license)
The idea of the setup : the transfer will be rehydrated + deduplicated again by CS-A to write them on CS-B B2D device ...
There is another story ... the IDB ... how to do you actually "replicate" your IDB ?