Cloud Based Disaster Recovery

The important of Business Continuity against human and machine related failures and outages is something the enterprises always keep in mind. However in the past maintaining secondary site for the applications that needs to be protected always incurred in high capital expenditures because all the infrastructure needs to be procured and provisioned ahead of time.

Positioning cloud platforms like Azure as a secondary site i.e disaster recovery site helps the organizations to get the best of economies of scale with respect to the infrastructure while enabling the enterprises to protect their applications against failures.

Azure Site Recovery is the complete framework and platform that facilitate a cloud based disaster recovery planning and setup for the enterprises. The following are the salient features of utilizing Azure Site Recovery Platform for cloud based disaster recovery.

  • Separating the technical details of the DR process from the applications, so that the entire DR process is decoupled from the applications and no need for any changes to the applications or business logic
  • Provide Disaster recovery support for a wide range of workloads which includes popular platforms like, VMWare, Hyper-V, Physical Servers and work loads include both Linux and Windows systems
  • No need for capital investment for expensive secondary data centers, rather position the Azure cloud as effective secondary site
  • Easier to set business rules regarding RTO (Recovery Time Objective) and RPO(Recovery Point Objective) as part of the DR Process
  • Easy to perform mock drills and failover to test the solution. The cost of the Virtual Machines incur only during the actual usage of secondary site and not all the time
  • Automation capabilities as part of the service, that will support the Administrators and engineers to perform the tasks quickly and without errors

However in spite of the support provided by the platform, Cloud Administrator who provide support on Azure Site Recovery should be aware of certain best practices, so that the enterprise applications are protected efficiently and in a cost effective manner on the Cloud

The following lists some of these best practices and points to be considered for setting up and administering the platform

Work Load Categorization

While Azure Site Recovery is built to take care most modern workloads, however it may not cover every component that exists in your organization and hence categorization of the workloads that needs to be protected by Azure Site Recovery and ensure that they are covered within the scope of Azure Site Recovery. While Microsoft documentation provides an extensive list of requirements for the on premise virtual machines, the following are some examples

  • Hyper-V hosts should be running on Windows Server 2012 R2
  • VMWare Vsphere ESX/ESXI hypervisors should be running on versions 6.0, 5.5, 5.1 with latest updates
  • Guest operating system for Windows should be Windows Server 2012 R2, Windows Server 2012, or Windows Server 2008 R2 with at least SP1
  • Guest operating system for Linux should be Red Hat Enterprise Linux 6.7; Centos 6.5, 6.6,6.7; Oracle Enterprise Linux 6.4, 6.5 running either the Red Hat compatible kernel or Unbreakable Enterprise Kernel Release 3 (UEK3), SUSE Linux Enterprise Server 11 SP3

There are also other limitations like, Operating System Disk Size, Disk Count, Hard disk format that play a role and hence this phase of categorization of work load is very important

Capacity Planning

Typical functioning of Azure Site Recovery requires that the on premise source machines to be replicated and created on server and also daily changes to the virtual machines are replicated over the network towards cloud. This requires that the infrastructure components in Cloud and the network bandwidth are planned ahead of time for smooth functioning of Azure Site Recovery

Microsoft recommends to use the Site Recovery Capacity Planner to analyze your source environment and workloads, and figure out bandwidth needs, server resources you’ll need in your source location, and the resources (virtual machines and storage etc), that you’ll need in your target location

Similarly Management Server which run On Premise plays a major role in synchronizing the replication. Microsoft has provided guide lines for configuration of Management Server and the same needs to be adhered.

Network Infrastructure

Though it can be classified under capacity planning, however network plays a major role in meeting the business continuity needs of the organization and hence it requires additional attention. Azure Site Recovery performs efficient replication over network, such that it replicates only the changed data and not the entire disk. But providing faster network bandwidth will ensure that the RPO & RTO needs of the organization are met

The following options will help to increase the replication network bandwidth. Site Recovery works with Azure ExpressRoute and WAN optimizers such as Riverbed

Azure ExpressRoute lets you create private connections between Azure datacenters and infrastructure on your premises or in a colocation environment. ExpressRoute connections don’t go over the public Internet. They offer more reliability, faster speeds, lower latencies, and higher security than typical Internet connections

Riverbed SteelHead CX for Microsoft Azure speeds the transfer of data and applications to the cloud from end users over the Internet and WAN. Overcome latency, bandwidth constraints and competition for resources among applications with data, application and transport streamlining for peak application service levels. SteelHead CX speeds migration to the public cloud and accelerates access for users from virtually any location.


While all of the activities required for setting up Azure Site Recovery can be done using Azure portal, most times it is cumbersome , error prone and not repeatable. However the good news is that all these steps can be performed using Azure Power Shell. This supports the new Azure Resource Manager option also

To summarize, more and more enterprises are realizing the advantages of cloud based disaster recovery setup. Azure Site Recovery is the robust platform and service that facilitates this for enterprises. By utilizing the Industry and Microsoft recommended best practices your journey to embrace Azure Site Recovery will be smoother and successful.