can vsphere replication be used to replicate vms between 2 Datacenters/Clusters in the same vcenter or does it have to be different vcenter?
Yes - see How vSphere Replication Works - Replication In a Single vCenter Server diagram.
But those replications are visible only in VR UI and can not be orchestrated by SRM. SRM does not support single vCenter for source and target of the same replication group.
SRM can use either:
- array based replication - per LUN data protection
- vSphere replication - per VM data protection
SRM does not support replicating within the same vCenter Server.
SRM provides recovery plans (invoking DR operations on multiple replicated VMs), test recovery, IP customization and other higher level functionality.
VR is per-VM and does not provide "test recovery" functionality.
|vSphere Replication appliances per vCenter Server instance|
|Maximum number of additional vSphere Replication servers per vSphere Replication appliance|
|Maximum number of protected virtual machines per vSphere Replication appliance|
|Maximum number of protected virtual machines per vSphere Replication server||200|
you need 1 VRA (the first VR appliance you deploy - this one handles the management) and 9 VRS to hit the 2000 VMs per vCenter. Each VRA/VRS supports a max of 200 VMs.
For more details on the difference between the appliances see the VR FAQ: Storage and Availability Technical Documents