Data Centers

Learn the pros and cons of remote-availability systems

If your organization's disaster recovery plan requires options for a wide-scale disaster, then you probably need to consider remote availability solutions. Mike Talon details the advantages and drawbacks of this recovery option.

When preparing for a disaster, the ability to fail over to a remote location with a minimum of downtime can definitely offer advantages. While remote-availability solutions offer both pros and cons, these solutions play a role in many business continuity plans.

On the plus side, RA offers the ability to resume data-system activities in another physical location in the event that the primary location becomes unavailable. While you may think that losing an entire physical location and/or data center to a disaster sounds like an unlikely occurrence, recent history offers several cases in point.

The blackout that plowed through the northeastern United States last August is one example; the series of devastating hurricanes in Florida earlier this year is another. Both of these disasters were unexpected, offered little--if any--opportunity for preparation or immediate action, and completely cut off employees and external resources from internal data systems. Those companies that had enacted RA solutions were able to get their information systems up and running at another physical location, one unaffected by either localized or more widespread disasters.

Tornados, fires, floods, blackouts, and other natural or even man-made disasters often give no warning, and nearly all of them cause at least temporary outages of primary data facilities. Without RA, once your uninterruptible power supply (UPS) or diesel generators give out, you're out of luck.

But RA systems also have some drawbacks. First of all, they're almost always a massive expense. You need space to store the alternate systems, which can be expensive.

While it's preferable to have this space completely under your organization's control, you can also rent or share space with other companies. But this space typically comes at a premium, since it traditionally offers data-center-level architecture and infrastructure. Your company could cut costs by using normal office space in another location, but this risks your failover solution causing a failure itself.

In addition, you need to provide redundant hardware. While it's often possible to protect multiple systems with a single system on the RA side, you must be aware of applications that don't support a many-to-one failover. For example, single-instance applications (such as Microsoft Exchange Server and many fax applications) nearly always require a one-to-one configuration for failover, both locally and remotely.

You must also ensure that you have enough bandwidth to the remote site to support replication of data via one or many methods. Hardware and software replication tools both require bandwidth, and different systems of the same general type can widely vary in their requirements.

Your organization may also need to transport backup media such as tapes and optical drive media to the DR site in order to perform restoration of those systems and components that you can't replicate for one reason or another.

In spite of these concerns, RA solutions are a very valid and, in many cases, vital part of an overall business continuity plan. If your organization can withstand the budget and other requirements, it's a great way to ensure that your systems can go beyond a single-site disaster.

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