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Administrator's Guide


How to Choose Device Classes

Define device classes to support the different tape devices, tape recording technologies, and storage media available to Tivoli Storage Manager.

Define additional tape device classes (with 3590 or CARTRIDGE device type) when your physical environment consists of different types of tape drives and storage media. However, do not mix devices that cannot read and write to the same media.

When defining tape device classes, consider:

Each tape device class is uniquely identified by its device class name and is characterized by its device type. Tivoli Storage Manager provides two tape device types: 3590 and CARTRIDGE. Examples of tape devices that support cartridge tape include the 3490 or 3480 Magnetic Tape Subsystems.

Do not mix non-compatible tape devices in a CARTRIDGE device class. For example, do not mix 3480 devices with 3490E devices because the server might not be able to satisfy a tape mount request to restore user data as demonstrated by the following scenario:

  1. A user backs up files, and the server attempts to store them in a tape storage pool assigned to a CARTRIDGE device class containing a 3480 and 3490E tape device.
  2. Because the 3480 is already in use, the server selects the 3490E tape device and requests a tape volume that provides the highest recording format. In this case, the server selects an Enhanced Capacity Cartridge System Tape volumes on which to store the backed up files.
  3. Later, the user requests to restore a file, which is located on the Enhanced Capacity Cartridge System Tape volume.
  4. Because the 3490E is already in use, the server selects the 3480 tape device. However, the 3480 tape device cannot read the Enhanced Capacity Cartridge System Tape volume. Therefore, the user must wait until the 3490E device is available before the restore operation can be completed.

The device type of CARTRIDGE is not the same as the predefined device class of CARTRIDGE. The CARTRIDGE device class has a device type of CARTRIDGE. You can have many different CARTRIDGE device classes with the device type of CARTRIDGE.

For example, based on the example introduced in Mapping Storage Pools to Device Classes and Devices, you could define two device classes named 36TRACK and 18TRACK with the CARTRIDGE device type as shown in Table 7.

Table 7. Naming CARTRIDGE Device Classes

Device Class Name Device Type Description
36TRACK CARTRIDGE Supports Cartridge System Tape volumes used with 3490E tape devices
18TRACK CARTRIDGE Supports Cartridge System Tape volumes used with 3480 or 3490 Base tape devices
Note:
The 3490 Base devices include Models A01, A02, A10, A20, B02, B04, B20, B40, D41, and D42. The 3490E devices include models C1A, C2A, C10, C11, and C22


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