I don't think it is a solution to my problem. I have to clarify our situation.
When trying to backup clients only connected to VLAN B, the disk agent is trying to connect the media agent on VLAN A. But there is no route between the both VLAN's. This will result in the following messages:
[Normal] From: VBDA@client.vlan-b "W:" Time: 23-11-2004 21:21:39 STARTING Disk Agent for client.vlan-b:/W "W:".
[Critical] From: BDA-NET@client.vlan-b "W:" Time: 23-11-2004 21:22:02 Cannot connect to Media Agent on system backupserver.vlan-a, port 3829 (IPC Cannot Connect System error:  Connection timed out) => aborting.
[Critical] From: VBDA@client.vlan-b "W:" Time: 23-11-2004 21:22:02 Unexpected close reading NET message => aborting.
[Normal] From: VBDA@client.vlan-b "W:" Time: 23-11-2004 21:22:02 ABORTED Disk Agent for client.vlan-b:/W "W:".
Can I specify a virtual server for the backup server and define a logical device for the same tape libray without any problem?
Thus you will need to import the network name for the media server on VLAN B as a virtual host.
And then create additional drives under the library, one for each physical drive, hosted by the client "media server name on VLAN B".
To determine the name of the client on VLAN A and VLAN B, I would assume a ping -a on the client should show two different names as being Pinged.
Assuming the cell manager can get to the IP address represented by "name on VLAN B".
Make sure that each drive which represents the same physical drive (ie, has the same drive index) has the same lockname configured in the Other tab of the Advanced Settings for the drive definitions.
Then your backups of clients on VLAN B should be using the drives "VLAN_B_D1", etc. or whatever you end up naming the drives which are hosted by the virtual client which is the network name of the media server on VLAN B.
We have the backup server connected to a backup lan (vlan a) and and a production lan (vlan b). The new servers are backupped using the dedicated backup lan, but we want also back up legacy servers only connected to the production lan.
I think it is the best solution for now, until the legacy servers are replaced by new servers with connections to both vlan's.