Few organisations make the move to virtualisation do so initially for disaster recovery reasons. Server
consolidation, data centre cooling and power cost savings are all more prevalent drivers, delivering tangible
cost savings.

These drivers are compelling and their direct return back to the business' bottom line make virtualisation an
excellent proposition. But they only tell part of the story. Once in place, the virtualisation infrastructure
itself lends itself to efficient and lower cost disaster recovery.

Within a virtualisation environment, the thousands of files and folders that make up each disk are usually
stored a single file. VMware has its .VMDK files. Microsoft and Citrix XenServer use .VHD. All of these are
single-file representations of a server disk partition. Wrapping the server's state into this single file
simplifies the backup process because one file equals one server.

This makes the requirements to add DR options to virtual backups much simpler and a lot less expensive. In
the physical world, DR is both expensive and an operational nightmare. In many environments, the only true
way to manage active failover DR was through the creation and administration of a secondary site with
redundant hot stand-by systems. For all but the largest organisations the cost of this is simply too high.

With virtualisation, it's possible to consider disaster recovery as little more than adding off-site
replication to backups. Several products exist that aid in the management and administration of this
replication, but the central theme in each is in enabling a mechanism for snapshots to be stored in another
facility for a worst case scenario. The greatest benefit with all of these products is that, depending on
your budget, the quantity and type of servers stored at the backup facility, and your recovery time
objective, there's a solution that can work for your environment.

Once off-site backup replication is in place, the decision on how to implement DR is based on both the level
of investment available and the required time to recovery. The least cost solution relies on your ability to
have new servers and storage delivered same or next day. Faster, more expensive approaches rely on having
cold or hot stand-by servers available, all pre-configured to run your virtualised environment as soon as the
backups have been restored to them.

In the DR situation it is likely that you can accept some application performance degradation, especially
considering that the number of staff using such applications may be less than normal. This means that your
requirements for hardware for DR need not directly reflect your normal production environment. Using the
flexibility of virtualisation you can simply increase the density of virtual machines per server.

Trustco provides a range of virtualisation solutions and advice. Please contact us to discuss your requirements.