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.
2 thoughts on “Azure Site Recovery: An Introduction”