Traditional PAM design is to have local DB to store everything.
But as the DB grows, replication takes more time and can cause frequent outages as the node can go out of sync.
Syncing the nodes also takes more time.
The idea is to allow configuration of external DB.
If all the PAM nodes are pointing to the same external DB, there would be no need to replicate. There is no need to synchronize.
In case if customer has sites globally and requires another instance of external DB, this DB would have its own replication(depending on what types of DB we support) but it would be significantly less bytes to transfer over WAN.
1. Customer can do a DB Backup directly from the DB side and not rely on PAM
2. PAM does not need to run DB locally, reducing CPU/RAM requirement.