Mirrored disaster recovery sites are a good fit for businesses that require rapid failover and have the right resources to build a duplicate data center.
In an enterprise environment, outages can deeply impact a business's revenue and reputation. Creating a mirrored disaster recovery site is one of the most effective ways to mitigate an outage.
Mirrored site disaster recovery means that an organization maintains exact replicas of its data and workloads across multiple sites. If an outage were to occur, a mirror site can automatically take over for the failed site, minimizing any disruption and financial loss.
For example, if an e-commerce site were to go offline, then the organization would lose sales for the duration of the outage. Additionally, some customers would inevitably go to the business's competitors and there will likely be some customers who never return. If that same business has a mirrored site in place for DR, critical business data would be securely stored at another location, with little to no impact on customers.
It's an appealing prospect for organizations with no tolerance for downtime, but there are some challenges and costs associated with using mirrored disaster recovery sites. Learn more about how mirrored DR sites work, where they work best and roadblocks that an organization might face when using one.
How does a mirrored DR site work?
A mirrored DR site is typically located in a different geographic area from the primary site. That way, if the primary site is affected by a regional power outage or natural disaster, the mirrored DR site is unlikely to be affected.
Mirror sites come in many forms. They can consist of a secondary data center, or simply be hosted within the public cloud. As long as the DR site is in a different region from the primary site, it should function as a secure alternate site for critical data.
In most cases, the hardware organizations use in the mirrored DR site is identical to that of the primary site. There are a couple of reasons for this. The first reason is that using identical hardware helps to prevent any compatibility problems that might otherwise occur when a workload fails over to the mirrored DR site.
A second reason for identical hardware is simply because when a failover does occur, the workload must perform just as well in the mirrored DR site as it does in the primary site. Because of this, the mirrored DR site must have the same hardware capacity and the same level of redundancy as the primary site.
When the costs of an outage exceeds the costs of maintaining the site, a mirrored site is a practical option.
For a mirrored DR site to be able to take over in the event of an outage, the primary site must be able to replicate data to the alternate site in real time. It's also important for the replication engine to be able to verify that the sites are in sync with one another and to automatically take corrective action if the sites become unsynchronized.
Finally, there must be a mechanism in place that can monitor site health in real time and automatically initiate a failover in the event of an outage.
When is a mirrored site practical?
Mirrored site disaster recovery can be tremendously beneficial, but the high costs of building and maintaining this type of site can make it impractical for some businesses. When the costs of an outage exceed the costs of maintaining the site, a mirrored site is a practical option. This might include workloads that are tied to mission-critical operations or for which there is a regulatory mandate for keeping certain workloads online during adverse circumstances.
Challenges of mirrored site disaster recovery
The most obvious challenges associated with creating a mirrored DR site are the costs and complexity associated with doing so. While it may be possible to reduce the costs by relying on cloud services rather than using a physical data center, there are still significant expenses involved.
Much of these costs are associated with bandwidth consumption. The workloads that an organization most often hosts on mirrored DR sites tend to produce high volume transactions. This makes a reliable, high bandwidth connection between sites an absolute must. Ensuring that the organization is not overpaying for bandwidth while making sure that adequate bandwidth is always available can be challenging.
Another significant challenge can be keeping the organization's data secure. It's difficult enough to keep a single site secure, both in terms of the physical location and the data it stores. but implementing a mirrored DR site means that an organization's IT staff must now work to secure two independent sites along with the data flowing between them.
A business must also perform regular maintenance on both sites and failover testing on a regular basis. The testing must be done in a way that will not accidentally cause an outage if something goes wrong during the test.
Because of these factors, organizations with larger security budgets, resources and teams will have an easier time securing both sites than a smaller organization.
Brien Posey is a 22-time Microsoft MVP and a commercial astronaut candidate. In his more than 30 years in IT, he has served as a lead network engineer for the U.S. Department of Defense and a network administrator for some of the largest insurance companies in America.
