Planning for Hyper-V disaster recovery without breaking the bank

You don't need costly solutions or complex architecture to extend Hyper-V disaster recovery to another site.

The tools to implement Hyper-V disaster recovery no longer require a Ph.D. in Windows clustering. Your existing storage area network may already have the replication technologies to mirror data between a primary and a backup site.

Hyper-V disaster recovery on a budget series For too long, the concepts surrounding Hyper-V disaster recovery have been muddied by incomplete information or overly complex technologies. That's the reason for this four-part series. You'll learn the six steps to implement Hyper-V disaster recovery on a budget. Now it may not be cheap. But at the same time, it's not so expensive that you need hundreds of thousands of dollars to get there.

 Hyper-V disaster recovery, formerly accessible to only the biggest enterprises, has steadily become a compelling addition for even the smallest environments. Because of Microsoft's improvements to Windows Failover Clustering in Windows Server 2008 Release to Manufacturing and R2, Hyper-V disaster recovery is now simple enough that you can build your own proof of concept during an afternoon.

Planning for Hyper-V disaster recovery
The advent of "virtualization everywhere" has increased the methods to prevent failure . In the old days, backups were the only prevention technology available. If you lost a file, a server or even an entire site, you probably asked, "Do I have backups?" and "How can I restore them?"

Today, virtual machines (VMs) enjoy significantly greater benefits. The problem is that categorizing the benefits of virtualization's and features is difficult. Given the myriad options for protecting VMs, keeping the possibilities straight is a challenge in itself.

The first step of Hyper-V disaster recovery planning is determining whether disaster recovery is actually what you want. Depending on your data center's tolerance for downtime and its recovery time objective, you may need something different. Consider the following options to protect VMs. The four capabilities below are listed in order of added cost for implementation.

• For more information on Hyper-V disaster recovery, check out the following resources. Citrix Essentials for Hyper-V automates disaster recovery   Disaster recovery strategies for Hyper-V Virtual disaster recovery and server backup case study

  Recovery. Recovery enables VMs to be brought back online from a single point in time and from disk or tape. While simple server recovery is arguably the least expensive method, it also takes the longest amount of time to restore a VM. Depending on your backup solution, this method has the least granularity: during a recovery, you don't know the exact restoration point. If you back up your VMs nightly, for example, the best restore point is "sometime in the past day." This technique works for some environments, but for others, unknown restoration points are unacceptable.
• High availability. High availability in Hyper-V environments is enabled through the Windows Failover Cluster service. Note that high availability has nothing to do with disaster recovery. Rather, high availability is a tool that assists in bringing VMs back online after a host failure. If a VM experiences a corruption or the blue screen of death or your entire site goes under water, high availability alone can't roll VMs back to a previous point in time.
• Disaster recovery. Hyper-V disaster recovery is also handled through the Windows Failover Cluster service, but in a more robust way. A Hyper-V cluster that supports disaster recovery extends to more than one geographic site. Also present are technologies that replicate VM storage among sites. This configuration ensures that VMs are quickly returned to service after a site failure.
• Fault tolerance. Some VM workloads need to stay operational no matter what. Take, for example, a production Exchange server or a mission-critical SQL database. If the application's primary instance experiences failure, a secondary instance immediately takes over processing client needs. This setup involves techniques and technology that differ from traditional disaster recovery and require additional planning.

This list also factors in the costs for technologies that you probably have in place. Recovering a single server, for example, requires a backup solution and disks or tapes that you likely have. On the other hand, a fault-tolerant design tends to require additional hardware as well as application-level replication that you'll probably need to purchase.

Planning for Hyper-V disaster recovery is obviously a big step. It ensures that you account for exactly the kinds of failures that are important to you.

Greg Shields is an independent author, instructor, Microsoft MVP and IT consultant based in Denver. He is a co-founder of Concentrated Technology LLC and has nearly 15 years of experience in IT architecture and enterprise administration. Shields specializes in Microsoft administration, systems management and monitoring, and virtualization. He is the author of several books, including Windows Server 2008: What's New/What's Changed, available from Sapien Press.

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