VMware vSphere Replication

Hi All,

Its been a few months I was thinking of writing about vSphere replication, why because we are using vSphere replication in our production environment and I can share some interesting things about this.

Let’s start…

vSphere Replication

Why we need a DR plan in place?

There are many situations it can interrupt your business or service which you provide to end user. It can be natural calamities, cyber attacks, human error, etc.. in such scenarios we should have DR plan in place and we have to make sure it will work as expected.

Most organizations will have a DR plan in place for their business continuity and it’s important too, there are many solutions available in the market for enabling DR solution for your environment. I already discussed Zerto Virtual Replication on my previous blog series and it’s a good tool for enabling hypervisor-based replication, most commonly used solution will be Array-based replication and it can be a costly solution.

VMware’s proprietary replication engine called vSphere Replication offers a very cost-effective DR solution without changing or purchasing new devices to your data center.

vSphere Replication protects virtual machines from partial or complete site failures by replicating the virtual machines between the following sites:

  • From a source site to a target site
  • Within a single site from one cluster to another
  • From multiple source sites to a shared remote target site

vSphere Replication provides several benefits as compared to storage-based replication.

  • Data protection at a lower cost per virtual machine.
  • A replication solution that allows flexibility in the storage vendor selection at the source and target sites.
  • The lower overall cost per replication.

You can use vSphere Replication with the vCenter Server Appliance or with a standard vCenter Server.

Image Credit: docs.vmware.com

How vSphere Replication Works?

In vSphere Replication, We can configure the replication of a virtual machine from a source site (Prod Site) to a target site (DR Site), monitor and manage the status of the replication, and recover the virtual machine at the target site.

When we configure a virtual machine for replication, the vSphere Replication agent sends changed blocks in the virtual machine disks from the source site to the target site. The changed blocks are applied to the copy of the virtual machine. This process occurs independently of the storage layer. vSphere Replication performs an initial full synchronization of the source virtual machine and its replica copy. We can use replication seeds to reduce the network traffic that is generated by data transfer during the initial full synchronization.

During replication configuration, we can set a recovery point objective (RPO) and enable retention of instances from multiple points in time (MPIT).

As an administrator, we can monitor and manage the status of the replication. We can view information for outgoing and incoming replications, local and remote site status, replication issues, and for warnings and errors.

When we manually recover a virtual machine, vSphere Replication creates a copy of the virtual machine connected to the replica disk but does not connect any of the virtual network cards to port groups. We have to review the recovery and status of the replica virtual machine and attach it to the networks. We can recover virtual machines at different points in time, such as the last known consistent state. vSphere Replication presents the retained instances as ordinary virtual machine snapshots to which we can revert the virtual machine.

vSphere Replication stores replication configuration data in its embedded database. We can also configure vSphere Replication to use an external database.

We can replicate a virtual machine between two sites. vSphere Replication is installed on both source and target sites. Only one vSphere Replication appliance is deployed on each vCenter Server. We can deploy additional vSphere Replication Servers.

Replication Between Two Sites

Image Credit: docs.vmware.com

Replication in a Single vCenter Server

We can also replicate a virtual machine between datastores at the same vCenter Server. In that topology one vCenter Server manages hosts at the source and at the target. Only one vSphere Replication appliance is deployed on the single vCenter Server. We can add multiple Additional vSphere Replication servers in a single vCenter Server to replicate virtual machines to other clusters.

To perform recovery, the vCenter Server managing the target datastore, the vSphere Replication appliance, and any additional vSphere Replication Servers managing the replication must be up and running.

Image Credit: docs.vmware.com

Replication to a Shared Target Site

We can replicate virtual machines to a shared target site.

Image Credit: docs.vmware.com

For more reference please visit docs.vmware.com

Components of vSphere Replication

vSphere Replication requires your vSphere infrastructure ready i.e ESXi hosts, vCenter Server, Storage infra, Network Infra and other components of infrastructure such as DNS, NTP etc..

vSphere Replication Appliance (VRA)

The vSphere replication appliance is the main component in the vSphere replication process and is registered to the vCenter. VRA stores its configuration and data in the embedded Postgres SQL database. We can also use an external SQL database.

The vSphere Replication Appliance also includes 1 vSphere Replication Server . Only 1 vSphere Replication Appliance can registered with a vCenter.

vSphere Replication Server (VRS)

The vSphere Replication Server in general is responsible for the replication job (data gathering from source-ESXi and data transferring to target-ESXi using NFC technology). One vSphere Replication Server (VRS) supports up to 200 replications. We can have a total of 10 VRS/vCenter Server.

That’s all guys.. will discuss more on vSphere Replication in an upcoming post stay tuned..🙂

Next blog post will be “Deploy vSphere Replication Appliance

I hope you enjoyed reading this post. Feel free to share this to others if it is worth sharing!!!

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Written by Sujith Surendran

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