vSphere Replication with Site Recovery Manager

[JodyWongGunvorU]

Hi,

I'm new to using SRM with vSphere Replication.  In the past I've always had storage array replication.

Versions:

SRM 8.1.0 (Build 8738384)

vSphere Replication 8.1.0 (Build 8744176)

So on to my question.

In the past when I've done it with Storage array replication, once I fail over I just reprotect and it only has to start replicating changes back to the source instead of having to re-seed the entire VMFS volume/LUN.

I've noticed that once I reprotect a VM after failover it will start a reverse replication and it has to replicate the entire VM again the other way!

Is there no way to make it keep the original VM files on the source and just replicate changes back when reversing? 

Does that make sense?

With the way I'm seeing vsphere replication work, it would take a long time to replicate all the VMs back.

[rcporto · Accepted solution]

Actually it only replicate back the changed blocks at DR site, but a task with Full Synchronization appear due the fact it is making the checksum of the disks, see:

How Site Recovery Manager Reprotects Virtual Machines with vSphere Replication

When performing reprotection with vSphere Replication, Site Recovery Manager uses the original VMDK files as initial copies during synchronization. The full synchronization that appears in the recovery steps mostly performs checksums, and only a small amount of data is transferred through the network.

[JodyWongGunvorU]

Hmm, is there some way for me to verify that?  It looks like it does a full sync back.

[JodyWongGunvorU]

So I just did a reprotect of a 50GB windows VM.  The amount of data needed to transfer constantly changes as the sync operation percentage goes up.  Is this normal? 

[rcporto]

Yes, because note that the checksum is in progress yet, so, while the checksum do not finish, maybe the amount of data to transfer will increase. But, at the end, only the different data will be transferred... the amount of time to the checksum finish will depends of your storage performance.