Database Administrator's Guide

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Data Caching Best Practices

Persistent data storage can be affected by two different failure modes:

  1. The FairCom DB Server process (FairCom-DB or ctreesql or ctsrvr) may be unexpectedly terminated while the operating system continues to run.
  2. A system crash or power loss may cause the entire system (including the FairCom DB Server and the operating system) to fail.

Case number 1 is the more common occurrence. Case number 2 can be partially avoided by using an uninterruptible power supply (UPS) to provide emergency power in case of a power failure.

As will be explained in this paper, data is typically placed in temporary cache memory before it is written to disk. In the case of the FairCom DB Server crashing, data written to the file system cache can still be written to disk. In the case of a complete system crash or power loss, data that is in temporary cache memory may be lost. The proper use of transaction processing can ensure that data files remain complete and consistent in the event of either type of occurrence.

Remember: No matter how many precautions you take, accidents (such as catastrophic failures and natural disasters) may happen that are beyond your ability to control.