In-Depth

Disaster Recovery to the Cloud: The Difference Between Backups and DR

Although the cloud is well known for its potential use as a backup target, public clouds are increasingly being used as a disaster recovery platform.

Although the cloud is well known for its potential use as a backup target, public clouds are increasingly being used as a disaster recovery platform.

The terms backup and disaster recovery are sometimes used interchangeably, but there's actually a considerable difference between the two. Backups refer to creating a restorable copy of an organization's data on a medium such as tape, or on disk or cloud storage. Conversely, disaster recovery is about maintaining continuity of business. The term refers to the ability to rapidly move a mission-critical workload off of a failed server, or out of a failed datacenter, and onto a server in another location.

In the past, disaster recovery had been largely cost-prohibitive because it involved either building a secondary datacenter, or leasing space in an expensive co-location facility. While there are costs associated with cloud-based disaster recovery, disaster recovery services in the cloud are far less expensive than other disaster recovery options. In fact, the cloud has made disaster recovery capabilities available to businesses of almost every size, whereas in the past only the largest enterprises could afford to implement disaster recovery capabilities.

Cloud-based disaster recovery essentially works by replicating virtual machines to a designated cloud. Once the initial replication cycle has completed, the virtual machine copies in the cloud are kept in sync with their production counterparts. That way, if an organization's production environment were to fail, the cloud-based virtual machine copy can be activated, thereby allowing critical services to remain online.

When it comes to implementing cloud-based disaster recovery, it's generally best to use a provider that specializes in disaster recovery rather than simply replicating virtual machines to the cloud yourself, and then trying to activate those virtual machines in the event of a disaster. There are two main reasons for this.

The first reason is that if a provider specializes in disaster recovery, then that provider will presumably have a support staff that's skilled in working through disaster recovery situations. A general-purpose cloud provider will be well-positioned to provide cloud infrastructure help, but may lack the expertise to guide a subscriber through a disaster recovery situation.

The second reason why it's a good idea to use a dedicated disaster recovery cloud is that it's typically impossible to replicate a virtual machine to the cloud, and then launch that virtual machine without making any changes to it. There's almost always some type of transformation that will be required before a virtual machine can function in the cloud. Some examples of this transformation include assigning an IP address that matches the cloud subnet, converting the virtual machine to run on the cloud provider's hypervisor of choice or configuring the virtual machine to use a different virtual switch. A dedicated disaster recovery provider may be able to orchestrate these and other tasks, so that you don't have to perform them manually.

About the Author

Brien Posey is a 16-time Microsoft MVP with decades of IT experience. As a freelance writer, Posey has written thousands of articles and contributed to several dozen books on a wide variety of IT topics. Prior to going freelance, Posey was a CIO for a national chain of hospitals and health care facilities. He has also served as a network administrator for some of the country's largest insurance companies and for the Department of Defense at Fort Knox. In addition to his continued work in IT, Posey has spent the last several years actively training as a commercial scientist-astronaut candidate in preparation to fly on a mission to study polar mesospheric clouds from space. You can follow his spaceflight training on his Web site.

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