A device class defines a device type for a set of volumes that can be created in a storage pool. Device classes are also important for storing database backups and for exporting and importing data.
About this task
Sequential-access device types include tape, and sequential-access disk. For random access storage, Tivoli® Storage Manager supports only the DISK device class, which is defined by Tivoli Storage Manager.
To define a device class, use the DEFINE DEVCLASS command and specify the DEVTYPE parameter. The DEVTYPE parameter assigns a device type to the device class. You can define multiple device classes for each device type. For example, you might want to specify different attributes for different storage pools that use the same type of tape drive. Variations might be required that are not specific to the device, but rather to how you want to use the device (for example, mount retention or mount limit). For all device types other than FILE or SERVER, you must define libraries and drives to Tivoli Storage Manager before you define device classes.
To update an existing device class definition, use the UPDATE DEVCLASS command. You can also delete a device class and query a device class by using the DELETE DEVCLASS and QUERY DEVCLASS commands.
| Task | Required privilege class |
|---|---|
| Define, update, or delete device classes | System or unrestricted storage |
| Request information about device classes | Any administrator |
- One device class can be associated with multiple storage pools, but each storage pool is associated with only one device class.
- If you include the DEVCONFIG option in the dsmserv.opt file, the files that you specify with that option are automatically updated with the results of the DEFINE DEVCLASS, UPDATE DEVCLASS, and DELETE DEVCLASS commands.
- Tivoli Storage Manager allows SCSI libraries to include tape drives of more than one device type. When you define the device class in this environment, you must declare a value for the FORMAT parameter.
See the following topics:
For details about commands and command parameters, see the Administrator's Reference.
See Mixed device types in libraries and Mixed device types in libraries for more information.
The examples in topics show how to perform tasks using the Tivoli Storage Manager command-line interface. For information about the commands, see the Administrator's Reference, or issue the HELP command from the command line of a Tivoli Storage Manager administrative client.
- Sequential-access device types
With Tivoli Storage Manager you can use tape devices, magnetic disk devices, removable media devices, and virtual volumes. - Defining tape device classes
Device class definitions for tapes include parameters that allow you to control storage operations. - Defining device classes for removable media devices
To access volumes that belong to this device class, the server requests that the removable media be mounted in drives. The server then opens a file on the media and reads or writes the file data. - Defining sequential-access disk (FILE) device classes
FILE device classes are used for storing data on disk in simulated storage volumes. The storage volumes are actually files. Data is written sequentially into the file system of the server machine. Because each volume in a FILE device class is actually a file, a volume name must be a fully qualified file name. - Defining LTO device classes
Special consideration is required to prevent or minimize problems when mixing different generations of LTO drives and media in a single library. LTO drive encryption might also be a consideration. - Defining SERVER device classes
SERVER device classes let you create volumes for one Tivoli Storage Manager server that exist as archived files in the storage hierarchy of another server, called a target server. These virtual volumes have the characteristics of sequential-access volumes such as tape. - Defining device classes for StorageTek VolSafe devices
StorageTek VolSafe brand Ultrium drives use media that cannot be overwritten. Do not use this media for short-term backups of client files, the server database, or export tapes. - Defining device classes for CENTERA devices
To use a Centera device, you must define a device class whose device type is CENTERA. - Obtaining information about device classes
You can choose to view a standard or detailed report for a device class. - How Tivoli Storage Manager fills volumes
The DEFINE DEVCLASS command has an optional ESTCAPACITY parameter that indicates the estimated capacity for sequential volumes associated with the device class. Tivoli Storage Manager uses the estimated capacity of volumes to determine the estimated capacity of a storage pool, and the estimated percent utilized.