Media pools

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Media pools

A media pool is a collection of tapes or disks to which the same management properties apply. All media in a Removable Storage system belong to a media pool, and each media pool holds only one type of media. Data management programs use media pools to gain access to specific tapes or disks within a library.

Using media pools, you can define properties that apply to a set of media. This is useful because Removable Storage allows multiple programs to share the same media within a single library. A library can include media from different media pools, each with different properties. A single media pool can span multiple libraries. You can also create hierarchies of media pools, or media pools that contain other media pools. For example, you can create a media pool for each specific media type required by a program, and then create another media pool that contains this collection of media pools. Media pools can contain either media or other media pools, but not both.

A Removable Storage system provides two classes of media pools: system and application.

System media pools include free media pools, unrecognized media pools, and import media pools. Removable Storage creates one free, one unrecognized, and one import media pool for each media type in your Removable Storage system. The system media pools are used to hold media that are not currently being used by an application.

Application media pools are created by data management programs such as Backup and Remote Storage, the latter for computers running Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; the 64-bit versions of Windows Server 2003, Enterprise Edition; or the 64-bit versions of Windows Server 2003, Datacenter Edition.

The different media pools are defined as follows:

• Unrecognized media pools contain blank (new) media and media that Removable Storage does not recognize. You should immediately move a new tape or disk from an unrecognized media pool to a free media pool so that the tape or disk can be used by applications, or remove it from the library.

  Unrecognized media are automatically deleted from the Removable Storage database when they are ejected from a library.

• Import media pools contain media that Removable Storage recognizes in the database but that have not been used before in a particular Removable Storage system. For example, media in an import media pool could be media from one office location that are introduced into a Removable Storage system at another office location.

  You can move media from import media pools to free media pools or application media pools so applications can use them.

• Free media pools contain media that are not currently in use by applications and do not contain useful data. Media in free media pools are available for use by applications.

  Application media pools can be configured to automatically draw media from free media pools when there are not sufficient media available in a particular application media pool. If this configuration is not implemented, you must manually move media from a free media pool when needed.

• Application media pools, created by data management applications (and by you), determine what media can be accessed by which applications.

  Media in an application media pool are controlled by that application or by an administrator. An application can use more than one media pool, and more than one application can share a single media pool. For example, Backup might use one media pool for full-backup and another media pool for incremental backup, each containing a different media type.

  There can be any number of application media pools in a Removable Storage system. Media that are currently reserved for use by an application, called allocated media, cannot be moved between media pools. Allocation controls how the media are used by applications.

The following illustration shows how media can move from one media pool to another.