Businesses often back up data to a variety of storage devices ranging from high-performance disk devices to slower and less expensive tape devices. Administrators must balance the data availability requirements of users with the costs of storage devices.
This section discusses how to evaluate your current environment to determine the device classes and storage pools for your ADSM storage.
Before configuring devices, evaluate the hardware available to ADSM.
ADSM expects to have exclusive use of the drives defined to it. If another application tries to use a drive defined to ADSM while ADSM is running, some ADSM server functions may fail.
| Note: | For sequential access devices, categorize the type of removable media based on capacity. For example, standard length cartridge tapes and longer length cartridge tapes require different device classes. |
Also consider the storage resources available on the target server. Ensure that the target server has enough storage space and drives to handle the load from the source server.
As an example of mapping devices to device classes, assume you have the following devices to use for ADSM storage:
You can map storage devices to device classes as shown in Table 1.
Table 1. Mapping Storage Devices to Device Classes
| Device Class | Description |
|---|---|
| DISK | Storage volumes that reside on the internal disk drive
ADSM provides one DISK device class that is already defined. You do not need and cannot define another device class for disk storage. |
| 8MM_CLASS | Storage volumes that are 8mm tapes, used with the drives in the automated library |
| DLT_CLASS | Storage volumes that are DLT tapes, used on the DLT drive |
You must define any device classes that you need for your removable media devices such as tape drives. See Chapter 8. "Defining Device Classes" for information on defining device classes to support your physical storage environment.
After you have categorized your storage devices, identify availability, space, and performance requirements for user data stored in ADSM storage. These requirements help you determine where to store data for different groups of users and different types of data. You can then create storage pools that are storage destinations for backed-up, archived, or space-managed files to match requirements.
For example, you determine that users in the business department have three requirements:
These files should be stored on disk. However, you need to ensure that data is moved from the disk to prevent it from becoming full. You can set up a storage hierarchy so that files can migrate automatically from disk to the automated tape library.
These files can be stored on 8mm tapes, using the automated library.
These files can be stored using the DLT drive.
To match user requirements to storage devices, you define storage pools,
device classes, and, for device types that require them, libraries and
drives. To set up the storage hierarchy so that data migrates from the
BACKUPPOOL to 8mm tapes, you specify BACKTAPE1 as the next storage pool for
BACKUPPOOL. See Table 2.
Table 2. Mapping Storage Pools to Device Classes, Libraries, and Drives
| Storage Pool | Device Class | Library (Hardware) | Drives | Volume Type | Storage Destination | ||
|---|---|---|---|---|---|---|---|
| BACKUPPOOL | DISK | -- | -- | Storage volumes on the internal disk drive | For a backup copy group for files requiring immediate access | ||
| BACKTAPE1 | 8MM_CLASS | AUTOLIB_8MM (Exabyte EXB-210) | DRIVE01, DRIVE02 | 8mm tapes | For overflow from the BACKUPPOOL and for archived data that is periodically accessed | ||
| BACKTAPE2 | DLT_CLASS | MANUAL_LIB (Manually mounted) | DRIVE03 | DLT tapes | For backup copy groups for files that are occasionally accessed | ||
| |||||||
Before a device can be used by ADSM, the device must be configured to the operating system as well as to ADSM. Table 3 summarizes the ADSM definitions that are required for different device types. For information on configuring devices, see the following sections:
Table 3. Required ADSM Definitions for Storage Devices
For devices that use removable media, you must choose a library type when you configure the devices. ADSM uses the library type to determine how volume mount operations are controlled on the drives in that library. The ADSM library types are:
In a MANUAL library, an operator mounts the volumes. Define a MANUAL library if you have one or more drives for which operators must mount volumes (drives that are not part of an automated library). You can combine drives with different device types, such as DLT and 8MM, in a single MANUAL library.
When the ADSM server determines that a volume needs to be mounted in a drive that is part of a MANUAL library, the server issues mount request messages that prompt an operator to mount the volume. The server sends these messages to the server console and to administrative clients that were started by using the special mount mode or console mode parameter.
For guidance on configuring a MANUAL library, see Chapter 5. "Using Removable Media Devices with ADSM". For information on how to monitor mount messages for a MANUAL library, see "Mount Operations for Manual Libraries".
A SCSI library is a collection of drives for which volume mounts and demounts are handled automatically by a robot or other mechanism. This type applies to automated libraries that are attached via a SCSI interface (other than the IBM 3494). Some examples of SCSI libraries are:
When you define a SCSI library to the ADSM server, you must specify the library device name. To mount and dismount a volume in a drive that resides in the SCSI library, ADSM uses the library name.
For guidance on configuring a SCSI library, see Chapter 5. "Using Removable Media Devices with ADSM". For an example of how to add volumes to a SCSI library, see "Label and Check In a Library Volume".
A 349X library is a collection of drives in an IBM 3494 Tape Library Dataserver. Volume mounts and demounts are handled automatically by the automation in the library.
When you define a 349X library to the ADSM server, you must specify the device name of one or more library management control points (LMCP). Each LMCP provides an independent interface to the robot mechanism within a given 349X library. To mount and dismount a volume in a drive that is in a 3494 library, ADSM uses an LMCP.
| Note: | For each 3494, you can define only one ADSM library. |
For guidance on configuring a 349X library, see Chapter 5. "Using Removable Media Devices with ADSM". For an example of how to add volumes to a 349X library, see "Label and Check In a Library Volume".
An ACSLS library is a collection of drives in an automated library that is controlled by the StorageTek software, Automated Cartridge System Library Software (ACSLS). ADSM can act as a client application to the ACSLS software to use the drives.
An EXTERNAL library is a collection of drives managed by a media management system that is not part of ADSM. ADSM provides an interface that allows external media management systems to operate in conjunction with the ADSM server. To use the interface for one or more devices, you must define a library with library type EXTERNAL.
For EXTERNAL libraries, ADSM uses the external media management system to perform the following functions:
The external media manager selects the appropriate drive for media access operations. You do not define the drives in an EXTERNAL library to ADSM.
When you issue the MOVE MEDIA or MOVE DRMEDIA command for media in EXTERNAL libraries, ADSM uses the external media management system to perform the following functions:
The EXTERNAL library type allows flexibility in grouping drives into libraries and storage pools. An EXTERNAL library may be one drive, a collection of drives, or even a part of an automated library.
For a definition of the interface that ADSM provides to the external media management system, see Appendix A. "External Media Management Interface Description".