Azure Site Recovery: An Introduction

When Microsoft released Azure Site Recovery, I have to say it caught my attention since it claimed to be a single solution which can orchestrate, and automate the protection, and recovery of on-premises physical servers and virtual machines based on Hyper-V or VMware with replication, failover and failback to Azure.

Azure Site Recovery v0.1

Components of Azure Site Recovery

  • On-Premises Process Server – This receives replication data from the Mobility Service (in-guest agent)  using disk based cache.  It is used to compress and encrypt data on-premises before sending it over internet/VPN/Express Route to the Master Target server in Azure
  • On-Premises Mobility Service – This can be pushed out automatically by the Process Server or performed manually.  Essentially it is an IO splitter that takes a write to disk, holds it in memory and sends it across to the Process Server
  • Azure Configuration Server – This is the brains, it co-ordinates communication between all components both on-premises and in Azure.  Each Configuration Server can support up to 100 source virtual machines.
  • Azure Master Target – Receives incoming replication traffic from the on-premises Process Server. Each protected VM is added as a VHD using ‘blob’ storage.
  • Replication – Azure Site Recovery uses streaming ‘a synch’ replication.  It’s worth noting that maximum throughput is 80Mbps when using Site to Site VPN or any form of normal internet connection.
  • Licensing – Is per protected VM

The diagram below shows the relationship between all the components.

Azure Site Recovery Components v0.1

What Are The Gotcha’s?

The gotcha’s I’m aware of at the moment are as follows:

  • Currently you are unable to perform test failovers.  The work round is to create ‘test VM’s’ failover to Azure and then destroy them.
  • You are unable to seed data into or out of Azure Site Recovery.  Thought needs to be how long it will take to protect virtual machines and failback to on-premises
  • Protected VM’s are limited to those supported in Azure
  • Protected VM’s can only migrate within their series type e.g. A1 to A4, but they cannot move into D series.

I’m sure Microsoft are working on these and will provide updates in the near future.

In my next blog post, I will start configuring Azure Site Recovery Manager with on-premises VMware virtual machines.

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