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.

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.

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.