Task | Required Privilege Class |
---|---|
Define device classes | System or unrestricted storage |
For any of the following devices, you must define libraries to the TSM server before you define device classes to access your sequential media:
See Chapter 6, Defining Drives and Libraries for information about defining drives and libraries.
If you include the DEVCONFIG option in the dsmserv.opt file, the files you specify with that option are automatically updated with the results of this command. When you use this option, the files specified are automatically updated whenever a device class, library, or drive is defined, updated, or deleted.
To use the 3570 or 3590 tape device, you must define a device class by issuing a DEFINE DEVCLASS command with the DEVTYPE parameter.
To use other tape devices that are supported by an HP-UX tape device driver, you must define a device class whose device type is GENERICTAPE. Do this by issuing a DEFINE DEVCLASS command with the parameter DEVTYPE=GENERICTAPE.
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 an HP-UX device driver, the TSM server is not aware of the following:
If you have a 4mm and an 8mm device, you must define separate manual libraries for each device.
If you have a manual library defined with two device classes of GENERICTAPE, ensure the recording formats are the same for both drives.
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.
You can limit the number of concurrent volume mounts so that your storage device resources are properly managed. The MOUNTLIMIT parameter specifies the maximum number of volumes that can be simultaneously mounted for a device class.
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 mount limit 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:
Do not specify a mount limit value that is greater than the number of associated available drives in your installation. If the server tries to mount as many volumes as specified by the mount limit and no drives are available for the required volume, an error occurs and client sessions may be terminated.
Note: | TSM cannot share drives between multiple device classes. |
TSM automatically cancels some processes to run other, higher priority processes. If the server is using all available drives in a device class to complete higher priority processes, lower priority processes must wait until a drive becomes available. For example, TSM cancels the process for a client backing up directly to tape if the drive being used is needed for a server migration or tape reclamation process. TSM cancels a tape reclamation process if the drive being used is needed for a client restore operation.
If processes are often canceled by other processes, consider whether you can make more drives available for TSM use. Otherwise, review your scheduling of operations to reduce the contention for drives.
The MOUNTWAIT parameter specifies 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.
The MOUNTRETENTION parameter specifies 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.
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 by 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 operation 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 an Idle Volume.
You can specify an estimated capacity value of any volumes defined to a storage pool categorized by a GENERICTAPE, 3570, or 3590 device class.
The default ESTCAPACITY value for a volume in a GENERICTAPE, 3570, or 3590 device class is 1GB. Specify a capacity appropriate for your particular tape drive.
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.
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.
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.
Also consider the resources available on the target server when setting mount limits. Do not set a high mount limit value if the target cannot move enough data or access enough data to satisfy all of the requests.
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.
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.
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, unless the DSMSERV_DIR environment variable is set. For more information on setting the environment variable, refer to Quick Start.
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 |
You must define a device class by issuing the DEFINE DEVCLASS command with the DEVTYPE=REMOVABLEFILE parameter. See Configuring Removable Media Devices (CD-ROM Support) for more information.
Other parameters specify how to manage storage operations involving the new device class:
You can update the device class information by issuing the UPDATE DEVCLASS command.
The LIBRARY parameter for a REMOVABLEFILE device class is used as described in Library.
The mount retention value for a REMOVABLEFILE device class is used as described in Mount Retention Period.
The mount wait value for a REMOVABLEFILE device class is used as described in Mount Wait Period.
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.
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.
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.
You can specify a maximum capacity value that restricts the size of files that are created on the target server to store data for the source server. The default MAXCAPACITY value is 500MB. The storage pool volumes of this device type are explicitly set to full when the volume is closed and dismounted.
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. (A value of 1 to 5 minutes is recommended.) This parameter can improve response time for sequential access media mounts by leaving previously mounted volumes online.
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.
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.
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.