Have anybody tested this configuration. Backup exec is vm and IBM TS3100 is connected to ESX with fibre. I can see the robotic library at backup exec management, but no tape drives. VM has one scsi connection to <ibm media> at configuration.
...that TN clearly states that as of ESX 4, only SCSI devices are supported...no mention of FC libraries.
If you can, make your BE server a physical server and you won't have any issues with this.
Alternatively, get hold of a SCSI device that you can present to the VM via SCSI pass-through, in which case you will get it to work.
However, speaking from experience, ESX/the VM tends to lose connectivity to the library meaning that it becomes a serious mission to troubleshoot the issue, often resulting in downtime.
This seems to be Alternate configuration and not fully supported. Please check the Hardware compatibility List of Backup Exec 2012.
For information Altrernative Configuration is a way of stating that we don't test it so don't officially support it. It might be possible to get it to work but you will still be unsupported unless you can prove that a supported configuration (in this case same library attached to physical server via the same type of HBA also has the problem.
As such if you want to be officially supported for physical tape drive access then use a physical media server do not run Backup Exec inside a VM.