TSM supports many devices for storing data. Devices known to TSM may be devices that exist as real physical devices, such as a disk drive or a tape drive. Devices may also be logical devices, such as files on a disk (FILE device type) or storage on another server (SERVER device type).
TSM represents physical and logical devices with administrator-defined storage objects: the device class, the library, and the drive. The storage objects, which you define when you configure devices for TSM, contain information for the management of devices and media.
At a minimum, each type of device requires a device class. The device class contains information for the management of devices and media that are of a specific device type. The device type determines whether TSM also requires a library and drive definition. For example, a manually mounted tape device requires a device class, a library, and a drive definition. See the following sections for details:
For a summary, see Table 4.
For details about devices that are supported, visit the Tivoli Storage Manager Web site at this URL:
Magnetic disk devices are the only devices in the random access category. All disk devices share the same TSM device type and device class: DISK. TSM has a predefined DISK device class.
Figure 3. Magnetic Disk Devices Are Represented by Only a Device Class
Figure 4 shows that a tape device is represented by a library and a drive in addition to a device class.
Sequential devices for which an operator must perform volume mounts require a different TSM library than devices that are associated with an automated library with robotics. TSM provides a manual library type for stand-alone devices that are loaded by an operator and automated library types for devices loaded by a robot.
Figure 4. Removable Media Devices Are Represented by a Library, Drive, and Device Class
Sequential devices that are managed by an external media management system require a library definition, but not a drive definition.
TSM allows administrators to create volumes on server disk space that have the characteristics of sequential access volumes such as tape. TSM supports these sequential volumes through the FILE device type. FILE is a sequential device type that, because it is on disk, does not require the administrator to define a library or drive object; only a device class is required.
You may want to use FILE volumes as a way to use disk storage without having to define volumes to TSM. FILE volumes can also be useful when transferring data for purposes such as electronic vaulting.
TSM allows administrators to create volumes that exist as archived files in the storage hierarchy of another TSM server. The volumes created are a special type of sequential access volume called a virtual volume. Virtual volumes have the characteristics of sequential access volumes such as tape. TSM supports virtual volumes through the SERVER device type. The administrator must define a device class and a server that will store the data. No library or drive definition is required.
Virtual volumes are useful for purposes such as the following: