An Exchange backup with granular restore enabled catalogs to the mailbox level. When you duplicate the image to tape, NetBackup extends the catalog by adding all the mailbox content. This takes some amount of time, because NetBackup has to bring up each database from the backup image. I think the catalog extension happens before NetBackup starts copying the data.
You can skip the granular catalog extension. It's an option on the duplication that's on by default.
Without the catalog extension, you have to duplicate the image back to disk before you can browse into the mailboxes.
Including Exchange in a VMware backup saves you data redundancy if you are also backing up the VM's. Unlike an MS-Windows policy, a VMware policy doesn't exclude the Exchange files. The granular browse and restore considerations are the same as for an Exchange policy.
With a VMware policy, you need to make sure Exchange discovery is working for you. With an Exchange policy, if the mailboxes aren't discovered ahead of time, they are enumerated during snapshot processing. A VMware backup doesn't enumerate the mailboxes if they haven't already been discovered.
A VMware policy only catalogs the Exchange databases and mailboxes for databases whose active copy is on the VM. That prevents redundancy when you are backing up multiple VMs that have copies of the database.
