3.9 Other Considerations

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As more businesses interconnect their computers at remote locations and run critical applications over WANs, they are discovering that financial and operational losses can mount quickly in the event of internetwork downtime. Businesses of all types and sizes are recognizing that disaster recovery plans are essential, regardless of the particular computing environment. The disaster recovery plan should be a formal document that has been signed off by senior management, information systems (IS) management, and all department heads. The following items should be addressed in any disaster recovery plan.

3.9.1 Uninterruptible Power Supplies

Uninterruptible power supplies (UPSs) are designed to provide temporary power so that attached computer systems and servers can be shut down properly to prevent data loss. UPSs are especially important in WANs. Because the distance between links can be thousands of miles, WANs are more susceptible to power problems than LAN segments. Therefore, using battery backups to protect against fluctuations and outages should always be the first line of defense.

While most data centers have UPSs, many remote sites typically do not, usually as a cost-saving measure. However, battery backup can be very inexpensive, costing only a few hundred dollars, which is cheap compared to the cost of indeterminate network downtime. Moreover, some UPSs have SNMP capabilities, which lets network managers monitor battery backup from the central management console. For instance, via SNMP, every UPS can be instructed to test itself once a week and report back if the test fails. The network manager can even be notified if the temperature levels in wiring closets rise above established thresholds.

3.9.2 Generators

To keep computers operating during a prolonged loss of power, a generator is required. The difference between a UPS and a generator is that the generator is capable of supplying much more power for longer periods of time. Using a fuel source such as oil, a generator can supply power indefinitely to keep data centers cool and computers running. Because generators can cost tens of thousands of dollars, many companies unwisely decide to skip this important component of the disaster recovery plan.

Unless an organization has experienced a lengthy outage that has disrupted daily business operations, this level of protection is often hard to justify. However, many office buildings already have generators to power lighting and elevators during electrical outages. For a fee, tenants can patch into the generator to keep data centers and networks operating.

3.9.3 Surge Suppressors

In storm-prone areas like the southeast, frequent electrical storms can put spikes or surges on telephone lines. Sudden bursts of electricity can destroy router links and cause adapters and modems to fail. To protect equipment attached to telephone lines, surge-suppression devices can be installed between the telephone line and the communications device. Surge suppressors condition the power lines to ensure a constant voltage level. Many modems and other network devices such as channel service units/data service units (CSU/DSUs) have surge suppressors built in. The disaster recovery plan should specify the use of surge suppressors wherever possible and they should be checked periodically to ensure proper operation.

3.9.4 Spare Parts Pooling

Most companies can afford to stockpile spare cables and cards, but not spare multiplexer and router components that are typically too expensive to inventory. Pooling these items with another area business that uses the same equipment can be an economical form of protection should disaster strike. Such businesses can be identified through user group and association meetings. The equipment vendor is another good source for this information.

After each party becomes familiar with the disaster recovery needs of the other, an agreement can be drawn up to pledge mutual assistance. Each party stocks half the necessary spare parts. The pool is drawn from as needed and restocked after the faulty parts come back from the vendor’s repair facilities.

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