Monday, September 30, 2013

Calculate Bandwidth Requirements using vSphere Replication Capacity Planning Appliance!

With a number of consulting engagements which I have done and the one's which I am working on, I have seen an increasing demand for using Host Based Replication solutions for data replication. In few of my recent projects, I have implemented VMware Site Recovery Manager with the combination of VMware vSphere Replication. 

I have written about vSphere Replication(VR) in the past and I am not surprised that a number of VMware customers are shifting focus from a storage based replication solution to a host based replication solution due to the cost-benefit and flexibility which comes with such a solution. In my projects I started with replicating simple web servers to DR site using VR and now customers are discussing database servers, exchange and other critical workloads to be replicated using vSphere Replication. With an out of the box integration with a solution such a as VMware Site Recovery Manager, building a DR environment for your Virtualized Datacenter has become extremely simple and cost effective.

The configuration of the replication appliance and SRM is as easy as going NEXT, NEXT & FINISH..., however the most common challenge has been around estimating the bandwidth requirements from Protected Site to Recovery Site for replication of workloads. One of the most commonly asked question is "How do I calculate the bandwidth requirements for replication?"

Honestly, this is not only a concern with any host based replication solution, but storage based replication too. I have done crazy things like capturing Writes on a workload in KB/Sec for days to get to an average change rate for a workload. This has to be done for each workload which you want to replicate and finally you will come to an estimate which is mostly no where close to the actual figure. Nevertheless, something is better than nothing.

During my recent discussions with VMware product management, I requested them to come out with a tool which can do this mathematics for a given workload and help us estimate the bandwidth requirements. This is critical for customers as an over-sized bandwidth requirement can lead to waste and ultimately unnecessary OPEX (Operational Expenditure) while an undersized bandwidth calculation can break the DR solution which can be catastrophic for any business.

The great news is that such a tool (fling) now exists and is called the 

As quoted by the developers "The vSphere Replication Capacity Planning Appliance allows administrators to model the network impact of a virtual machine replication without producing actual replication traffic. The appliance provides command-line tools to configure replication for any VM in a vSphere Virtual Center. The replication is established in preview mode and thus requires no storage space. Networking traffic, required for the replication, is measured and displayed in an easy-to-understand graphical format that allows you to estimate the network bandwidth required."

As I write this article, I am downloading the OVA and would try this in my lab to see what do I get out of this. Since this is a fling, you might want to know that there is no official support for Flings but if this works, it would be great to see this as a part of the vSphere Replication Appliance.

To download a copy for yourself visit the following link -

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