15.10 - Benefits - Teradata Database

Teradata Database Teradata Virtual Storage

Teradata Database

Mixing storage technologies (device types, speeds, capacities) in a parallel architecture typically requires significant user interaction to ensure that the most frequently accessed data is stored on the fastest storage. Teradata VS automates this process, transparently moving this important data to storage media that offers the fastest I/O performance.

Data temperature is an indication of the relative frequency of access to a quantity of data: frequently accessed data is considered to be “hot”, and infrequently accessed data is considered to be “cold.” Teradata VS maintains statistics on temperatures of cylinders, logical groups of row data, and also is aware of the relative data access speeds provided by of the various kinds of storage media (the grades of the media). This allows Teradata VS to intelligently migrate more frequently accessed data to faster physical storage. As data access patterns change, Teradata VS can move cylinders to faster or slower physical storage within each clique to improve system performance over time.

Teradata VS can migrate all data from one physical storage device to another to prepare for removal or replacement of the physical device. This process is called evacuation. Complete data evacuation requires a system restart, but Teradata VS supports a soft evacuation feature that allows much of the data to be migrated while the system remains online. This can minimize system down time when evacuations are necessary.

Device management features of Teradata VS provide the ability to pool storage within each clique. Each storage device (pdisk) can be shared, if necessary, by all AMPs in a clique. If the number of storage devices is not a multiple of the number of AMPs in the clique, the extra storage is shared. Consequently, storage can be added to the system in smaller increments, as needs and opportunities arise.

Teradata VS supports the use of different disk types, capacities, and speeds used within cliques. As new types of physical storage (such as new disk sizes and types) become available and are certified for use with Teradata Database, they can be added to any clique.