Category Archives: vSphere Replication

vSphere Replication & Multi Point in Time Snapshots

By | 25/10/2017

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 read more

Replicating VM between sites using vSphere Replication

By | 25/10/2017

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 read more

vSphere Replication 6.0 Compression Method

By | 23/10/2017

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. 

data compression-0.PNG

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. read more

Isolating vSphere Replication Traffic

By | 21/10/2017

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.
  • The vSCSI filter periodically replicates the changed data to the vSphere Replication Appliance at the target site
  • The vSphere Replication Appliance sends the replicated data to the vSphere host with access to the target datastore over NFC

Why we need VR traffic isolation?

By isolating the vSphere replication traffic from critical business network traffic’s helps in enhancing the network performance in the data center. You can use a dedicated uplink for VR traffic and you can apply prioritization and QoS methods individually on different traffic types. Also monitoring and troubleshooting becomes easy when each traffic is flowing through a dedicated link.

You isolate the network traffic to the vSphere Replication Server by dedicating a VMKernel NIC on each ESXi host on the primary site that sends data to the vSphere Replication Server.

Lets jump into lab now and get our hands dirty.

1: Set Up a VMkernel Adapter for VR traffic on a source and destination Esxi hosts.At source site the vmkernel adapter should be enabled only for VR traffic and nothing else.

My lab config looks like below. I have 3 Esxi host in source site and all hosts are connected to the replication portgroup. 



At destination site, I have 2 Esxi host and both are connected to portgroup which is dedicated for vSphere replication


2: Shutdown the VR appliance and add a new network adapter to use for incoming replication traffic. 

Post adding the NIC, power on the VR appliance.


3: Login to VR appliance VAMI interface and configure the eth 1 (newly added nic) by navigating to Network > Address tab.

In my lab, my management traffic flows on network and for replication traffic I have created a new subnet :


4: Use the IP which we set on eth1 to be used for storage traffic as shown below.


5: Add static route on VR appliance for newly added NIC

vrs01:~ # route add -net gw dev eth1

You can also add the static routes information to /etc/sysconfig/network/routes file so that routes are persistent across reboots.

vrs01:~ # cat /etc/sysconfig/network/routes
default - - dev eth1

Verify the newly added route appears in routing table

vrs01:~ # netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
default UG 0 0 0 eth0
loopback * U 0 0 0 lo
link-local * U 0 0 0 eth0 UG 0 0 0 eth1 * U 0 0 0 eth0

6: Add static route on Esxi host. Please see VMware KB-2001426 for this.

# esxcli network ip route ipv4 add --gateway --network read more

Using Custom Certificates in vSphere Replication

By | 25/06/2016

In this post we will be working on using a custom signed certificates (CA Signed) on vSphere Replication Appliance.

Unlike vCenter Server, there is no automated way of replacing the default certificates on VR appliance and all it needs a bit of manual effort. VMware has outlined the steps in the official KB-2080395 to do so.

Before performing these steps, make sure you have already replaced the default certificates on your vCenter Server.

vSphere Replication appliance ships with openssl and you can use this to generate the certificate signing requests for the vSphere Replication appliance read more

Unregistering vSphere Replication Plugin from vCenter

By | 05/05/2016

This week I was having some trouble with vSphere Replication appliances in my lab and decided to rip apart my replication setup. I logined to my VR appliance VAMI address and unregistered VRMS from vCenter Server. Deleted my replication appliance in order to deploy it from scratch.

To my surprise vSphere Replication plugin was still present in my vCenter Server, even after I logged out and logged in back to webclient.


I tried to reboot my vCenter Server to see if it clears the plugin, but that trick didn’t worked for me. read more

vSphere Replication-Part 5: Replicating and Recovering VM’s using VR

By | 18/04/2016

In last post of this series we saw how to deploy vSphere Replication appliance. In this appliance we will see the basic configurations of the replication appliance and will replicate a VM from source site to DR site. Also we will see how to recover VM on target (DR) site when your primary site has gone down.

If you have missed earlier posts of this series then you can access the same by clicking on below links:

1:Introduction to vSphere Replication

2: Lab Setup

3: Preparing vCenter for Replication

4: Deploying vSphere Replication Appliance read more

vSphere Replication-Part 4: Deploying vSphere replication Appliance

By | 26/03/2016

In last post of this series we saw the prerequisites that needs to be configured in vCenter Server before start deploying the replication appliance. In this post we will see how to deploy vSphere Replication appliance.

If you have missed earlier posts of this series then you can access the same by clicking on below links:

1:Introduction to vSphere Replication

2: Lab Setup

3: Preparing vCenter for Replication

Let’s dive into the installation process of replication appliance.

The vSphere Replication appliance is available in  ovf format. Download the ovf file from here. read more

vSphere Replication-Part 3: Preparing vCenter for Replication

By | 25/03/2016

In last post of this series we had a look on pieces of infrastructure that needs to be made ready before starting and using vSphere Replication. In this post we will see what are the vCenter server requirements before start deploying vSphere Replication appliances and start configuring it.

If you have missed earlier posts of this series then you can access the same by clicking on below links:

1:Introduction to vSphere Replication

2: Lab Setup

Following settings are required to be configured in vCenter Server prior to deploying and configuring vSphere replication Appliances. read more

vSphere Replication-Part 2: Lab Setup

By | 28/02/2016

In first part of this series vSphere Replication Introduction we have discussed what is vSphere Replication and how it works. We also discussed the architecture and components involved and saw the possible use cases where vSphere Replication can be used.

In this post we will look on how to setup lab for deployment of vSphere Replication and what pieces of infrastructure should be ready before we start using vSphere Replication.

I am going to use cross site replication in my lab so here is my lab components: read more

vSphere Replication-Part 1: Introduction

By | 27/02/2016

I am quite a new candidate to vSphere Replication and have seen quite a few appliances deployed in our production environment as we are offering Disaster Recovery to Cloud (DR2C) services to our customers in vCloud Air and often have to troubleshoot issues related to replication.

So to understand how disaster recovery works and what should be the area we should be looking for while troubleshooting replication issues, I decided to try my hand on learning and deploying vSphere Replication in my lab. read more