SAN failure lost the backupexec database.

Nothing has changed within Backup Exec in regards Inventory / Catalog operations of tape libraries.
If you have lost your BE database as the title indicates, then you need to run not just an inventory but a catalog job as well to really see what is on these tapes (in case you need to do a restore).

If the tapes had encrypted sets then passphrase will also be needed to run the catalog job post the Inventory of all tapes ( make sure you run an inventory on all available tapes first before starting the catalog