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| About Database Dynamic Storage Tiering | ||
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More and more data is being retained. Eventually, some of the data is no longer needed as frequently, but still takes up a large amount of disk space. Database Dynamic Storage Tiering matches data storage with the data's usage requirements so that data is relocated based on requirements determined by the database administrator (DBA). The feature enables you to manage your data so that less-frequently used data can be moved to slower, less expensive disks, allowing frequently-accessed data to be stored on the faster disks for quicker retrieval. Storage classes are used to designate which disks make up a particular tier.
There are two common ways of defining storage classes:
Performance, or storage, cost class: The most-used class consists of fast, expensive disks. When data is no longer needed on a regular basis, the data can be moved to a different class that is made up of slower, less expensive disks.
Resilience class: Each class consists of non-mirrored volumes, mirrored volumes, and n-way mirrored volumes.
For example, a database is usually made up of data, an index, and logs. The data could be set up with a three-way mirror because data is critical. The index could be set up with a two-way mirror because the index is important, but can be recreated. The logs are not required on a daily basis and could be set up with no mirroring.
Dynamic Storage Tiering (DST) policies control initial file location and the circumstances under which existing files are relocated. These policies cause the files to which they apply to be created and extended on specific subsets of a file systems's volume set, known as placement classes. The files are relocated to volumes in other placement classes when they meet specified naming, timing, access rate, and storage capacity-related conditions.
In addition to preset policies, you can manually move files to faster or slower storage, when necessary. You can run reports that list active policies, display file activity, display volume usage, or show file statistics.