Tivoli Storage Manager for Windows: Administrator's Guide


Defining and Updating Device Classes for Sequential Media


Task Required Privilege Class
Defining and updating device classes System or unrestricted storage

You can define and update multiple device classes for each device type. The following sections show how to define the device classes for each supported device type.

If you are using device classes that have any of the following device types, you must define libraries and drives to the TSM server before you define device classes to access your sequential media:

For information about defining drives and libraries, see Chapter 7, Managing Drives and Libraries.

If the DEVCONFIG option is included in the dsmserv.opt file, the files you specify with that option are automatically updated whenever a device class, library, or drive is defined, updated, or deleted.

Defining and Updating Device Classes for Tape Devices

To use tape devices, you must define a device class by issuing a DEFINE DEVCLASS command with the DEVTYPE parameter.

TSM Device Type Device
3570 IBM 3570
3590 IBM 3590
4MM 4mm
8MM 8mm
DLT Digital linear tape
DTF Digital tape format
ECARTRIDGE StorageTek cartridge tape drives such as STK SD-3 and 9490
LTO IBM 3580, 3581, 3583, 3584
NAS Network-attached storage (NAS) device used for backup
QIC Quarter-inch cartridge
GENERICTAPE Supported tape devices

Other parameters specify how to manage server storage operations involving the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Mount Limit

You can limit the number of drives that the device class has access to at one time with the MOUNTLIMIT parameter.

The default mount limit value is DRIVES. The DRIVES parameter indicates that every time a mount point is allocated, the number of drives online and defined to the library is used to calculate the true mountlimit value. The maximum value for this parameter is 256 and the minimum value is 0. A zero value prevents new transactions from gaining access to the storage pool.

When selecting a mount limit for a device class, be sure to consider the following questions:

Mount Wait Period

You can use the MOUNTWAIT parameter to specify the maximum amount of time, in minutes, that the server waits for a manual (or operator controlled) volume mount request to be satisfied before canceling the request. The default mount wait period is 60 minutes. The maximum value for this parameter is 9999 minutes.

Mount Retention Period

You can use the MOUNTRETENTION parameter to specify the amount of time that a mounted volume should remain mounted after its last I/O activity. If this idle time limit is reached, the server dismounts the volume. The default mount retention period is 60 minutes. The maximum value for this parameter is 9999 minutes.

Note:
|A device class with DEVType=NAS allows only a value of zero |(0). |

For example, if the mount retention value is 60, and a mounted volume remains idle for 60 minutes, then the server dismounts the volume.

If a volume is used frequently, you can improve performance by setting a longer mount retention period to avoid unnecessary mount and dismount operations.

If mount operations are being handled with manual, operator-assisted activities, you may want to use a large mount retention period. For example, if only one operator supports your entire operation on a weekend, then define a long mount retention period so that the operator is not being asked to mount volumes every few minutes.

While TSM has a volume mounted, the drive is allocated to TSM and cannot be used for anything else. If you need to free the drive for other uses, you can cancel TSM operations that are using the drive and then dismount the volume. For example, you can cancel server migration or backup operations. For information on how to cancel processes and dismount volumes, see Canceling Server Processes and Dismounting Idle Volumes.

Tape Label Prefix

By using the PREFIX parameter, you can specify a prefix value that is used to construct the file name string that is stored in the label area of each tape volume.

The prefix string is used as the prefix of the file name that is written to the label of each tape.

The default value for the tape label prefix string is ADSM.

Recording Format

You can use the FORMAT parameter to specify the recording format used by TSM when writing data to a tape.

See the Administrator's Reference for information about the recording formats for the following device classes:

Use the FORMAT=DRIVE parameter only if all drives that can be accessed by the device class are identical. If some drives associated with a device class support a higher density format than others, mount errors can occur when you specify FORMAT=DRIVE.

For example, suppose a device class uses two incompatible devices such as an IBM 7208-001 and a 7208-011. The server might select the high-density recording format of 8500 for each of two new volumes. Later, if the two volumes are to be mounted concurrently, one fails because only one of the drives is capable of the high-density recording format.

The recording format that TSM uses for a given tape volume is selected when the first piece of data is written to the volume. Note that updating the FORMAT parameter of a device class does not affect tapes that already contain data until those tapes are rewritten from the beginning. This process may happen after a volume is reclaimed or deleted, or after all of the data on the volume expires.

Estimated Capacity Value

You can either accept the default estimated capacity value for a given device class or explicitly specify an estimated capacity that you want the server to use instead of the default. For tape device classes, the default values selected by the server depend on the recording format used to write data to the volume.

Note:
|For a device class with DEVType=NAS, this value is required. |

See Administrator's Reference for information about the estimated capacities of recording formats for the following device classes:

Library

Before the server can mount a volume, it must know which drives can be used to satisfy the mount request. This process is done by specifying the library when the device class is defined. The library must contain drives that can be used to mount the volume.

Note that only one library can be associated with a given device class. However, multiple device classes can reference the same library. In this case, you must ensure that the sum of the mount limit values for each such device class does not exceed the number of drives defined in the referenced library.

There is no default value for this parameter. It is required, and so must be specified when the device class is defined.

Defining and Updating Device Classes for Generic Tape Devices

To use tape devices that are supported by a Windows tape device driver you must define a device class whose device type is GENERICTAPE. Do this by issuing a DEFINE DEVCLASS command with the DEVTYPE parameter.

When you specify the GENERICTAPE device type for a manual library that has more than one drive defined, ensure that the device types and recording formats of the drives are compatible. Because the devices are controlled by a Windows device driver, the TSM server is not aware of the following:

Other parameters specify how to manage server storage operations involving the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Library

The LIBRARY parameter for GENERICTAPE device class is used as described in Library.

Mount Limit

The mount limit value for GENERICTAPE device class is used as described in Mount Limit.

Mount Retention

The mount retention value for GENERICTAPE device class is used as described in Mount Retention Period.

Estimated Capacity

You can specify an estimated capacity value of any volumes defined to a storage pool categorized by a GENERICTAPE device class.

The default ESTCAPACITY value for a volume in a GENERICTAPE device class is 1GB. Specify a capacity appropriate for your particular tape drive.

Mount Wait

The mount wait value for GENERICTAPE device class is used as described in Mount Wait Period.

Defining and Updating Device Classes for Optical Devices

To use optical media, you must define a device class by issuing the DEFINE DEVCLASS command with a DEVTYPE parameter for one of the optical devices:

Parameter Description
OPTICAL 5.25-inch rewritable optical media
WORM 5.25-inch write-once read-many optical media

Other parameters specify how to manage data storage operations involving the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Library

The LIBRARY parameter for OPTICAL and WORM device classes is used as described in Library.

Mount Limit

The mount limit value for OPTICAL and WORM device classes is used as described in Mount Limit.

Mount Wait Period

The mount wait period for OPTICAL and WORM device classes is used as described in Mount Wait Period.

Mount Retention Period

The mount retention period for OPTICAL and WORM device classes is used as described in Mount Retention Period.

Estimated Capacity Value

TSM estimates the capacity of the volumes in a storage pool based on the parameters assigned to the device class that is associated with the storage pool. The estimated capacity value is used by TSM when making decisions about when to initiate a reclamation process for volumes in the storage pool. It is also used to generate storage pool and volume reports. As a volume is written and filled, the server determines the actual capacity of the volume and uses this instead of the estimated capacity.

You can either accept the default estimated capacity value for a given device class or explicitly specify an estimated capacity that you want the server to use instead of the default.

Recording Format

You can use the FORMAT parameter to specify the recording format used by TSM when writing data to an optical cartridge.

See the Administrator's Reference for information about the recording formats for the OPTICAL and WORM device classes.

Defining and Updating Device Classes for Removable File System Devices

To use local, removable file system devices that use removable media, you must define a device class whose device type is REMOVABLEFILE. These devices are supported by a Windows device driver, but a TSM device type does not otherwise exist.

Removable media is treated as single-sided media. Therefore, double-sided cartridges are treated as two individual volumes in this device class. Define double-sided media as two separate volumes.

You can issue a DEFINE DEVCLASS command with the DEVTYPE parameter.

Other parameters specify how to manage server storage operations involving the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Library

The LIBRARY parameter for the REMOVABLEFILE device class is used as described in Library.

Mount Limit

The mount limit value for REMOVABLEFILE device class is used as described in Mount Limit.

Mount Retention

The mount retention value for REMOVABLEFILE device class is used as described in Mount Retention Period.

Maximum Capacity

You can specify a maximum capacity value that restricts the size of volumes (that is, files) associated with a REMOVABLEFILE device class. Use the MAXCAPACITY parameter with the DEFINE DEVCLASS command.

Because the server opens only one file per physical removable medium, specify a value such that the one file makes full use of your media capacity. When the server detects that a volume has reached a size equal to the maximum capacity, it treats the volume as full and stores any new data on a different volume.

The default MAXCAPACITY value for a REMOVABLEFILE device class is the remaining space in the file system where the removable media volume is added to TSM.

Mount Wait

The mount wait value for REMOVABLEFILE device class is used as described in Mount Wait Period.

Defining and Updating FILE Device Classes

The FILE device type is used for special device classes whose storage volumes are not physical units, such as tape or optical cartridges, but simulated storage volumes. Data is written sequentially into standard files in the file system of the server machine. You can define this device class by issuing a DEFINE DEVCLASS command with the DEVTYPE=FILE parameter.

Because each volume in a FILE device class is actually a file, a volume name is a fully qualified file name string.

When you define the FILE device class, you can supply the following parameters to manage server storage operations for the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Mount Limit

The mount limit value for FILE device classes is used to restrict the number of mount points (volumes or files) that can be concurrently opened for access by server storage and retrieval operations. Any attempts to access more volumes than indicated by the mount limit causes the requester to wait. The default value is 1. The maximum value for this parameter is 256.

Note:
The MOUNTLIMIT=DRIVES parameter is not valid for the FILE device class.

When selecting a mount limit for this device class, consider how many TSM processes you want to run at the same time.

TSM automatically cancels some processes to run other, higher priority processes. If the server is using all available mount points in a device class to complete higher priority processes, lower priority processes must wait until a mount point becomes available. For example, TSM cancels the process for a client backup if the mount point being used is needed for a server migration or reclamation process. TSM cancels a reclamation process if the mount point being used is needed for a client restore operation.

If processes are often cancelled by other processes, consider whether you can make more mount points available for TSM use. Otherwise, review your scheduling of operations to reduce the contention for resources.

Maximum Capacity Value

You can specify a maximum capacity value that restricts the size of volumes (that is, files) associated with a FILE device class. Use the MAXCAPACITY parameter of the DEFINE DEVCLASS command. When the server detects that a volume has reached a size equal to the maximum capacity, it treats the volume as full and stores any new data on a different volume.

The default MAXCAPACITY value for a FILE device class is 4MB.

Directory

You can specify the directory location of the files used in the FILES device class. The default is the current working directory of the server at the time the command is issued.

The directory name identifies the location where the server places the files that represent storage volumes for this device class. While processing the command, the server expands the specified directory name into its fully qualified form, starting from the root directory.

Later, if the server needs to allocate a scratch volume, it creates a new file in this directory. The following lists the file name extension created by the server for scratch volumes depending on the type of data that is stored.

For scratch volumes used to store this data: The file extension is:
Client data .BFS
Export .EXP
Database backup .DBB
Database dump .DMP

Defining and Updating SERVER Device Classes

The SERVER device type is used for special device classes whose storage volumes are not directly attached to this server. A volume with device type SERVER consists of one or more files archived in the server storage of another server, called a target server. You can define this device class by issuing a DEFINE DEVCLASS command with the DEVTYPE=SERVER parameter. For information about how to use a SERVER device class, see Using Virtual Volumes to Store Data on Another Server.

Other parameters specify how to manage data storage operations for the new device class:

You can update the device class information by issuing the UPDATE DEVCLASS command.

Server Name

The TSM server on which you define a SERVER device class is called a source server. The source server uses the SERVER device class to store data on another TSM server, called a target server.

When defining a SERVER device class, specify the name of the target server. The target server must already be defined by using the DEFINE SERVER command. See Using Virtual Volumes to Store Data on Another Server for more information.

Mount Limit

Use the mount limit value for SERVER device classes to restrict the number of simultaneous sessions between the source server and the target server. Any attempts to access more sessions than indicated by the mount limit causes the requester to wait. The default mount limit value is 1. The maximum value for this parameter is 256.

Note:
The MOUNTLIMIT=DRIVES parameter is not valid for the SERVER device class.

When selecting a mount limit, consider your network load balancing and how many TSM processes you want to run at the same time.

TSM automatically cancels some processes to run other, higher priority processes. If the server is using all available sessions in a device class to complete higher priority processes, lower priority processes must wait until a session becomes available. For example, TSM cancels the process for a client backup if a session is needed for a server migration or reclamation process. TSM cancels a reclamation process if the session being used is needed for a client restore operation.

If processes are often cancelled by other processes, consider whether you can make more sessions available for TSM use. Otherwise, review your scheduling of operations to reduce the contention for network resources.

Maximum Capacity Value

You can specify a maximum capacity value that restricts the size of objects that are created on the target server to store data for the source server. The default MAXCAPACITY value is 500MB.

Mount Retention

You can specify the amount of time, in minutes, to retain an idle sequential access volume before dismounting it. The default value is 60. The maximum value you can specify for this parameter is 9999. This parameter can improve response time for sequential access media mounts by leaving previously mounted volumes online.

Prefix

You can specify a prefix that the source server will use as the beginning portion of the high-level archive file name on the target server.

Retry Period

You can specify a retry period for communications with the target server. When there is a communications failure, this period determines the amount of time during which the source server continues to attempt to connect to the target server.

Retry Interval

You can specify how often the source server tries to connect to the target server when there is a communications failure. During the retry period, the source server tries to connect again as often as indicated by the retry interval.


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