You can use the 5 minute Recovery Point Objective (RPO) if the target and the source sites use Virtual SAN storage.
vSphere Replication 6.1 displays the 5 minute RPO setting only when the target and the source site use Virtual SAN storage.
If you change the target site to a site that does not use Virtual SAN, you cannot set the RPO value to less than 15 minutes.
The 5 minute RPO is limited to 100 VMs per Virtual SAN cluster.
You can retain the 5 minute RPO setting when you reconfigure replication and change the source or target location to a site that does not use Virtual SAN.
If you select the OS quiescing option while configuring replication, you cannot use an RPO value lower than 15 minutes.