Hot Spots: Step one for DR: Server virtualization

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A virtualized DR site
Consolidating physical servers at the DR site eliminates the need for one-to-one mirrored physical machines and can deliver savings in power and cooling, management and maintenance. The portability of virtual machines also means that failback can occur to the original location or to a new one: either a virtual machine or a physical system with dissimilar hardware.

Another advantage is the ability to test DR more efficiently. Regular DR testing--confirming failover and failback processes, and testing documentation--is necessary to ensure DR preparedness. In server virtualization environments, DR tests can be performed on a virtual machine without affecting another machine or the primary production system. Tests can be run in more realistic situations (during peak hours, with peak-time staff and on actual DR hardware) without impacting normal operations and with less risk should something go awry.

P2V- or V2V-based replication offers a big improvement over tape-based backup/recovery, especially when it comes to recovery point objectives (RPOs). With tape, an organization could lose up to a full day's data because tape backup usually occurs once per day. With replication, incremental changes are captured as they happen, and can then be replicated to one or more local or remote virtual machines. Tape-based backup is more affordable, but the recovery

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process is slower, more manual and error-prone. Replication also lets you effectively meet budget and recovery requirements.

More sophisticated clustering solutions take immediate action by starting up apps at the DR site and making the application available to users. Clustering meets aggressive recovery objectives, but can be more complex and costly to implement and manage. Clustering solutions have moved into the virtual world and can protect virtual machines in much the same way they protect physical machines.

With server virtualization, remote replication becomes cost-effective for organizations that haven't previously implemented DR or for tiers of application servers that may not have justified aggressive RTO objectives, but would still be painful to manually recover.

This was first published in April 2008

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