by Craig S. Mullins
Database systems require data files to store the data under management. These files, or data sets, reside on storage media. So storage management should be a key part of the database operations required of a DBA. Unfortunately, storage is sometimes relegated to an afterthought; after all, don’t we have storage administrators who deal with our disk arrays? But this way of thinking is misguided. To succeed, database administration and storage administration need to cooperate and work together.
For database systems, storage usually will be accomplished by means of fixed disk drives or disk subsystems. Today that means RAID arrays in most cases. But database storage can also mean non-
Some part of the DBA’s job must involve planning for the actual storage of database data. To adequately perform this part of the job, the DBA must be conversant in the actual physical storage mechanisms available to be used for data storage. Furthermore, the DBA must understand the ways in which the abstract concept of data within a DBMS interacts with the physical storage of data on persistent storage media.
Most disk storage technologies can work with most DBMS products. But, some storage technologies are better-
For mission critical applications data integrity can be more important than data availability. If the storage media is unreliable and a failure causes data corruption, the lost data can be more of a problem than the downtime. It is imperative, therefore, that database storage solutions protect the data at all costs.
Database performance is I/O dependent – the faster the DBMS can complete an I/O operation the faster the database application will run. Remember that data retrieval from storage media takes much longer to complete than data retrieval from cache or memory. For this reason most modern storage systems provide their own caching mechanism to pre-
Managing storage in today’s dynamic environment is a challenging DBA task. Goals to consider while building a storage system for your database include:
To accomplish these goals, DBAs and the storage administrators must cooperate with each other. DBAs need to remember that other types of data that are not stored in the DBMS are stored on disk, too. Databases use storage differently than non-
From Database Trends and Applications, September 2010.
© 2012 Craig S. Mullins,