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Administrator's Guide


Tivoli Storage Manager Storage Objects

The Tivoli Storage Manager devices and media are represented by objects that you define and that are stored in the database. The objects contain information about the devices and media. You can query, update, and delete the objects. The storage objects are:

The following sections describe these objects.

Library, Drive, and Device Class

These three objects taken together represent a physical storage entity as shown in Figure 8.

Figure 8. Removable Media Devices Are Represented by a Library, Drive, and Device Class

Removable Media Devices Are Represented by a Library, Drive, and Device Class

A physical library is a collection of one or more drives that share similar media mounting requirements. That is, the drive may be mounted by an operator or by an automated mounting mechanism. A library object definition specifies the library type (for example, SCSI or 349X) and other characteristics associated with the library type (for example, the category numbers used by an IBM 3494 library for private and scratch volumes).

Each drive mechanism within a device that uses removable media is represented by a drive object. For devices with multiple drives, including automated libraries, each drive is separately defined and must be associated with a library. Drive definitions can include such information as the element address (for drives in SCSI libraries), how often the drive is cleaned (for tape drives), and whether or not the drive is online.

Each device defined to Tivoli Storage Manager is associated with one device class. That device class specifies a device type and media management information, such as recording format, estimated capacity, and labeling prefixes. Device classes for a tape or optical drives, must also specify a library.

A device type identifies a device as a member of a group of devices that share similar media characteristics. For example, the 8MM device type applies to 8mm tape drives. Device types include a variety of removable media types and also FILE and SERVER:

Removable Media
Tivoli Storage Manager provides a set of specified removable media device types, such as 8MM for 8mm tape devices, or REMOVABLEFILE for Jaz or Zip drives. The GENERICTAPE device type is provided to support certain devices that do not use the Tivoli Storage Manager device driver. See Chapter 9, Defining Device Classes and Administrator's Reference for more information about supported removable media device types.

FILE
This device type allows you to create sequential volumes by creating files on disk storage. To the server, these files have the characteristics of a tape volume. The FILE device type does not require you to define library or drive objects; only a device class is required.

You can use FILE volumes as a way to use disk storage without having to define volumes. FILE volumes can also be useful when transferring data for purposes such as electronic vaulting.

SERVER
This device type allows you to create volumes for one Tivoli Storage Manager server that exist as archived files in the storage hierarchy of another server. These virtual volumes have the characteristics of sequential access volumes such as tape. You must define a device class and a target server. No library or drive definition is required.

Virtual volumes can be used for the following:

See Using Virtual Volumes to Store Data on Another Server.

Storage Pool and Storage Pool Volume

A storage pool is a collection of storage pool volumes that are associated with one device class and one media type. For example, a storage pool that is associated with a device class for 8mm tape volumes contains only 8mm tape volumes. You can control the characteristics of storage pools, such as whether scratch volumes are used. For details about defining storage pools, see Chapter 10, Managing Storage Pools and Volumes.

Tivoli Storage Manager supplies default disk storage pools. For more information, see Configuring Random Access Volumes on Disk Devices.

Figure 9 shows storage pool volumes grouped into a storage pool. Each storage pool represents only one type of media. For example, a storage pool for 8mm devices represents collections of only 8mm tapes.

Figure 9. Relationships of Storage Pool Volumes, Storage Pools, and Media

Relationships of Storage Pool Volumes, Storage Pools, and Media

For DISK device classes, you must define volumes. For other device classes, such as tape and FILE, you can allow the server to dynamically acquire scratch volumes and define those volumes as needed. For details, see Preparing Volumes for Random Access Storage Pools and Preparing Volumes for Sequential Access Storage Pools.

One or more device classes are associated with one library, which can contain multiple drives. When you define a storage pool, you associate the pool with a device class. Volumes are associated with pools. Figure 10 shows these relationships.

Figure 10. Relationships between Storage and Device Objects

Relationships between Storage and Device Objects

For more information about the storage pool and volume objects, see Chapter 10, Managing Storage Pools and Volumes.

Data Mover

Data movers are devices that accept requests to transfer data from applications such as Tivoli Storage Manager. Data movers transfer data:

You must define a data mover if you will be using network-attached storage or server-free data movement. Among other characteristics, you must specify the data format that will be used and the data mover address or world wide name (WWN) and serial number.

For more information about the data mover object, see Defining Data Movers and Managing Data Movers.

Path

Paths allow access to drives, disks, and libraries and drives. A path definition specifies a source and a destination. The source accesses the destination, but data can flow in either direction between the source and destination. Here are a few examples of paths:

For more information about the path object, see Defining Paths and Managing Paths.

Server

You need to define a server object, for the following purposes:

Among other characteristics, you must specify the server TCP/IP address.

How Tivoli Storage Manager Mounts and Dismounts Removable Media

When data is to be stored in or retrieved from a storage pool, the server does the following:

  1. Selects a volume from the storage pool. The selection is based on the type of operation:

    Retrieval
    The name of the volume that contains the data to be retrieved is stored in the database.

    Store
    If a defined volume in the storage pool can be used, the server selects that volume.

    If no defined volumes in the storage pool can be used, and if the storage pool allows it, the server selects a scratch volume.

  2. Checks the device class associated with the storage pool to determine the name of the library that contains the drives to be used for the operation.
  3. Mounts the volume:
  4. Dismounts the volume when it has finished accessing the volume and the mount retention period has elapsed.


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