Difference between vSphere Replication and Array based
replication in SRM 5.0
vSphere replication advantages:-
1.
No requirement for enterprise array based
replication at both sites.
2.
Replication between heterogeneous storage,
whatever that storage vendor or protocol might be at each site (so long as it’s
supported on the HCL).
3.
Replication of local or direct attached storage
is possible in VR whereas in Array based replication, the data to be replicated
must reside on SAN.
4.
It allows per VM replication.
5.
It’s included in the cost of SRM licensing. No
extra VMware or array based replication licenses are needed.
vSphere replication disadvantages:-
1.
Re-Protect and Automated Failback is only
supported with array-replicated virtual machines. Virtual machines configured
with vSphere Replication cannot be failed back automatically to the original
site using existing recovery plans. This feature is available in SRM 5.1.
2.
Cannot replicate powered off virtual machines.
Therefore it cannot replicate templates as well. VM would be replicated once
they are powered on.
3.
Cannot replicate FT VMs. Note that array based
replication can be used to protect FT VMs but once recovered they are no longer
FT enabled.
4.
vSphere Replication cannot be used in
conjunction with physical raw disk mapping (RDM).
5.
VR has file level consistency only (no
application consistency). However, in SRM 5.1, it does offer some type of
application consistency.
6.
Asynchronous replication is not supported by VR.
Array based replication will replicate a VMware based snapshot hierarchy to the
destination site while leaving them intact. VR can replicate VMs with snapshots
but they will be consolidated at the destination site. This is again based on the principle that
only changes are replicated to the destination site.
7.
Cannot replicate vApp consistency groups.
8.
With vSphere Replication, RPO is 15 min or
higher.
9.
VR does not work with virtual disks opened in
“multi-writer mode” which is how MSCS VMs are configured.
10.
Losing a vSphere host means that the vRA and the
current replication state of a VM or VMs is also lost. In the event of HA failover, a full-sync must
be performed for these VMs once they are powered on at the new host (and vRA).
11.
In band VR requires additional open TCP ports:
a.
31031 for initial replication
b.
44046 for ongoing replication
12.
VR requires vSphere 5 hosts at both the protected
and recovery sites while array based replication follows only general SRM 5.0
minimum requirements of vCenter 5.0 and hosts which can be 3.5, 4.x, and/or
5.0.
13.
Cannot replicate linked clone trees (Lab
Manager, vCD, View, etc.)
Other points to consider:-
- Network address translation (NAT) is not supported with SRM: When configuring vSphere Replication, you must configure the vSphere Replication Server (VR server) with an IP address that is visible to both the protected vSphere Replication Management Server (VRM Server) and the recovery VRM Server.
- Neither array-based replication nor vSphere Replication support using Storage DRS: Storage vMotion of a replicated virtual machine results in a full sync, where both the primary and the recovery side disks are read and hashed, and these hashes are exchanged over the wire which can result in heavy I/O, and this can cause latency on the datastore.
