Veritas NetBackup™ Troubleshooting Guide

About disaster recovery

Data backup is essential to any data protection strategy, especially a strategy that is expected to assist in disaster recovery. Regularly backing up data and therefore being able to restore that data within a specified time frame are important components of recovery. Regardless of any other recovery provisions, backup protects against data loss from complete system failure. And off-site storage of backup images protects against damage to your on-site media or against a disaster that damages or destroys your facility or site.

To perform recovery successfully, the data must be tracked. Knowing at what point in time the data was backed up allows your organization to assess the information that cannot be recovered. Configure your data backup schedules to allow your organization to achieve its recovery point objective (RPO). The RPO is the point in time before which you cannot accept lost data. If your organization can accept one day's data loss, your backup schedule should be at least daily. That way you can achieve an RPO of one day before any disaster.

Your organization also may have a recovery time objective (RTO), which is the expected recovery time or how long it takes to recover. Recovery time is a function of the type of disaster and of the methods that are used for recovery. You may have multiple RTOs, depending on which services your organization must recover when.

High availability technologies can make the recovery point very close or even identical to the point of failure or disaster. They also can provide very short recovery times. However, the closer your RTO and RPO are to the failure point, the more expensive it is to build and maintain the systems that are required to achieve recovery. Your analysis of the costs and benefits of various recovery strategies should be part of your organization's recovery planning.

Effective disaster recovery requires procedures specific to an environment. These procedures provide detailed information regarding preparation for and recovering from a disaster. Use the disaster recovery information in this chapter as a model only; evaluate and then develop your own disaster recovery plans and procedures.

The specific procedures that replace failed disks, build partitions and logical volumes, and reinstall operating systems can be complicated and time consuming. Such procedures are beyond the scope of this manual. Appropriate vendor-specific information should be referenced.