Hello,
Are those datacenters going to be in a different site. If yes, then you should consider below mentioned points before getting that configuration implemented:
1. Are you using PGP Server as a Gateway server? If yes, then how many emails are being processed by it?
2. What kind of WAN connection is going to exist between the cluster nodes and how much bandwidth it can handle ?
3. It will take less than 1mb/second for a pure replication between 2 servers
4. It will take additional bandwidth of around 10kb/second for pure PDF / Web Messenger replication
Best Regards,
Ankush Sharma