|Lesson 3||Business considerations |
|Objective||Identify business considerations related to the DBA role.|
DBA Role Business Considerations
The failure of a database can incur great costs associated with the time
needed to recover the database and any data that is lost. You must make management aware of the time that will be needed to recover so management can quantify the costs related to your time estimates. In addition, all levels of management must approve the backup and recovery strategy that you define, before you implement it. This lesson reviews most of the business issues that you need to consider as you prepare your backup and recovery strategy.
Time to Recover Database
When you review the types of failures that could occur with your database, you should also identify the approximate amount of time that will be required to recover the database. The most important estimate is the time it will take to recover from a complete failure of your system. This will provide a worse case time estimate for your database and company to return to normal operations. Other less drastic estimates may relate to the loss of redo log file or disk drive. There are no hard and fast rules that will give you exact recovery times. You will need to test certain failure scenarios and recover the
database. Obviously, recovering a 10MB database will be quicker than recovering a 10TB database.
Time between failures
With proper information, a DBA should be able to predict how often certain types of failures will occur. Most hardware manufactures provide
information about the failure rate of their components. Good backup and recovery logs will provide a history of database corruption with an
indication of user or software generated problems. During this course we will discuss various Oracle tools to identify what can occur in your system and help plan for these failures. Management can support this process by providing adequate resources to maintain the system and provide education and training programs for the users.
You are looking for trends. Here are some examples that I encountered:
- The last day of every other month special processing would put an undue burden on the system and the operating system would crash.
- Window washers splashed water down a heating vent every month. This caused an electrical short the next day that crashed my disk drives.
- An unshielded wire running down an infrequently used elevator shaft flooded with waterthe network once a month and caused my backup to take 2 hours rather than 30 minutes.
Our event and backup logs helped use to track down and eventually fix these problems.
Reviewing your Strategy
Your backup and recovery strategy must evolve as your company's business changes. It is important that the DBA and management review the backup and recovery plan on a periodic basis. It's also important that the DBA be aware of potential new uses of data or new business processes that will affect the backup and recovery plan. A good example of this is a company moving to the Internet. A backup plan that brings your company's database down from 12am to 2am every day may be fine for today's environment. If your company develops a strong Internet presence, you might not be
able to afford to bring the database down at all.
As a DBA, you and management must determine how much pain your company can tolerate.
The next lesson explains factors involved in evaluating operational concerns.
DBA Business Considerations - Exercsie