The following TSM storage objects are collections of information that the TSM server uses to communicate with devices and to manage media:
An administrator for TSM defines these objects.
Each device is associated with one TSM device class. A device class contains information about the device type and the way the device manages its media. See More on the Contents of the Device Class and Chapter 7, Defining Device Classes for more detailed information about device classes.
For devices that access data randomly, TSM provides a device class named DISK that is already defined and cannot be changed.
For devices such as tape drives that access data sequentially, the administrator must define the device class. Devices that access data sequentially also include FILE and SERVER device types. For FILE device classes, data resides in files on the server's disk storage. For SERVER device classes, data resides in the storage of another TSM server.
If the sequential device is a tape drive, the device class is associated with a library. The library object is required for sequential devices because of the variations in media type (for example, 4mm and 8mm) and because of the need to manage multiple drives and automation.
A TSM library is an administrator-defined collection of one or more drives that share similar media mounting requirements. The library can include an automated mounting mechanism. Each tape device must be associated with a TSM library.
A TSM library can contain more than one physical device and can contain different types of devices. Use different libraries to identify devices that are mounted by different means (for example, an operator instead of robotics). You can define these types of libraries:
See Chapter 6, Defining Drives and Libraries for more information about TSM libraries.
Each drive mechanism within a tape device is represented by a TSM drive. For devices with multiple drives, including automated libraries, each drive is separately defined to TSM. Each drive is associated with a TSM library. See Chapter 6, Defining Drives and Libraries for more information about drives.
A storage pool is a named collection of storage volumes that are associated with one device class. Each storage pool represents a collection of volumes that are the same media type. For example, a storage pool that is associated with a device class for 8mm tape contains only 8mm tape volumes. You can control the characteristics of storage pools, such as whether scratch volumes are used, by specifying parameters. For details on the parameters, see Chapter 8, Managing Storage Pools and Volumes.
TSM supplies default disk storage pools that are named BACKUPPOOL, ARCHIVEPOOL, and SPACEMGPOOL. For more information, see Configuring Random Access Volumes on Disk Devices.
A TSM storage pool volume represents space on media that is available for storing client data. A storage pool volume is associated with a storage pool. For example, 8mm tapes and DLT tapes become storage pool volumes when they are assigned to a TSM storage pool.
See Chapter 8, Managing Storage Pools and Volumes for more information about TSM storage pool volumes.
To store data in the storage of another TSM server, you use a SERVER device type in the device class. You also define a server object to communicate with the target server (where data is actually stored).
When you define a server object to one TSM server (a source server), you specify the communication attributes necessary for establishing a connection to another TSM server (a target server). The source server can then use the target server as a sequential device for storing data. This data on the target server is one or more archived files that are stored on behalf of the source server.
The contents of a device class are determined by whether the device accesses the data on its media randomly or sequentially.
Devices that access their media randomly share a common TSM device type. TSM provides a single, random-access device class, named DISK. You cannot define other random access device classes. You do not define a TSM library for random access devices.
Random access device types store data in blocks of storage that can be scattered across the available space on a disk. As the server deletes data that has expired, the space occupied by that data can be reused.
Tape devices, FILE device types, and SERVER device types are members of the sequential access category of devices. All of these devices access their data sequentially. A device class for a sequential device contains a device type and media management information.
For tape devices, the device class also specifies a library. Figure 6 shows the contents of a device class for a tape device.
Figure 6. Contents of a Device Class for Tape Devices
Sequential access device types begin to store data at the beginning of a volume, and append new data after existing data. As data is deleted or expired, the space is not immediately reused. The server can reclaim space later by using the reclamation process (see Reclaiming Space in Sequential Access Storage Pools for details).
Every sequential access device class requires one of the TSM device types as part of its definition. A device type identifies a device as a member of a group of devices that share similar media characteristics. TSM provides device types for different devices. For example, TSM provides a 3590 device type for IBM 3590 tape drives.
FILE is a sequential device type in TSM that allows the administrator to create sequential volumes by creating files on disk storage. To the TSM server, these files have the characteristics of a tape volume.
A device type called REMOVABLEFILE supports devices that have removable media and are attached to the server as local, removable file systems. TSM sees each unit of media, for example an optical disk, as a single, sequential access file.
The sequential device type called SERVER allows the server to store data on another TSM server. This data has the characteristics of a tape volume from the view of the source server. On the target server, this data appears as archived files that belong to a special type of node.
For tape devices (3570, 3590 and GENERICTAPE), you must specify a library in the device class definition. The library you specify must be one that you have defined to TSM, as discussed in Library.
Every sequential access device class contains media management information, such as recording format and labeling prefixes.
For more information about how TSM helps to manage media, see the following: