When configuring replication of a virtual machine, you might have noticed the option “Point in time instances” aka PIT. This setting allow for some snapshots to be maintained at the DR site for the replicated VM at certain intervals.  

During replication, vSphere Replication replicates all aspects of the virtual machine to the target site, including any potential viruses and corrupted applications. The benefit being that if a guest is corrupted, we have multiple points in time to failover from in case the corruption already replicated across sites

vSphere Replication retains a number of snapshot instances of the virtual machine on the target site based on the retention policy that you specify. vSphere Replication supports maximum of 24 snapshot instances. After you recover a virtual machine, you can revert it to a specific snapshot.

Multiple Point In Time (MPIT) recovery was first introduced in vSphere replication 5.5 and it enables an administrator to recover a virtual machine to the latest replicated copy at the target site and then revert, or “roll back,” that virtual machine to a previous point in time.… Read More

Once your primary and DR site is ready, you can start replicating VM’s between the sites and test the failover/failback etc to ensure your disaster recovery plans are functioning well and you will be protected when actual disaster happens in your on-premise datacenter.

In this post we will learn how to replicate VM from one vCenter to another which is in DR site. Lets get started.

Navigate to VM and template view in vCenter server in your source site and select the VM which you want to replicate to the DR site. Right click on the VM and chose All vSphere Replication Actions > Configure replication

vSphere Replication can be used to replicate VM’s to the local DR site as well as to a cloud provider side such as vCloud Air . In our example we are going for a local DR site replication so I chose Replicate to a vCenter Server. … Read More

With vSphere Replication 6.0, VMware added a new feature named “Network Compression” and you have noticed this while configuring replication for a virtual machine. 

What is Network Compression?

It is a method for compressing the replication data that is transferred through the network which helps in saving network bandwidth and might help reduce the amount of buffer memory used on the vSphere Replication server. However, compressing and decompressing data requires more CPU resources on both the source site and the server that manages the target datastore.

Do you really need network compression in your infrastructure?

vSphere Replication uses CBT technique to replicate changed blocks to a DR site (which commonly exists in cloud these days) and the DR site is usually connected to primary site via a WAN link. These WAN links typically have limited bandwidth or high latency. Network compression can save your precious WAN bandwidth.

VR data compression support

vSphere Replication 6.0 supports end-to-end compression when the source and target ESXi hosts are also version 6.0.… Read More

Prior to vSphere 6, the replication traffic was sent and received using the management interfaces of ESXi and VRA appliances. With vSphere 6 it is possible to send the replication traffic over a separate dedicated interface.

By default, the vSphere Replication appliance has one VM network adapter that is used for various traffic types.

• Management traffic between vSphere Replication Management Server and vSphere Replication Server.

• Replication traffic from the source ESXi hosts to the vSphere Replication Server.

• Traffic between vCenter Server and vSphere Replication Management Server.

• NFC (Network File Copy) traffic which is used to copy VM replication data from the vSphere Replication Server appliance at the target site to the destination datastores.

VR Traffic Flow

We will use below image for understanding the flow of replication traffic

Typically these are the sequence of events that take places when a VM is configured for replication and initial sync has completed:

• As data is written to VM disks, the writes pass through the vSCSI filter on the host where the VM is running
• The vSCSI filter monitors all I/O to the VMs disks and tracks those changes.