In database terminology, a tablespace bridges the gap between the logical representation of data in tables, and the physical storage of that data on disk. A tablespace encompasses one or more units of storage specified by the user (often called 'containers'). Tables are then created in tablespaces. This gives the user control over where different data is stored physically. One advantage of being able to do this is to make efficient or parallel use of avialable hardware. While one drive is accessing data from one set of tables, another drive can be accessing data from different tables simultaneously. One common configuration is to split indexes and tables into different tablespaces, so that to look up entries in the index, one need not wait for the table data itself to become available, and vice versa.