DEFINE DEVCLASS (Define an 8MM device class)
Use the 8MM device class when you are using 8 mm tape devices.
Privilege class
To issue this command, you must have system privilege or unrestricted storage privilege.
Syntax
Parameters
- device_class_name (Required)
- Specifies the name of the device class to be defined. The maximum length of the device class name is 30 characters.
- LIBRary (Required)
- Specifies the name of the defined library object that contains the 8 mm tape drives used by this device class. For information about defining a library object, see the DEFINE LIBRARY command.
- DEVType=8MM (Required)
- Specifies that the 8MM device type is assigned to the device class. 8MM indicates that 8 mm tape devices are assigned to this device class.
- WORM
- Specifies whether the drives use WORM (write once, read many) media. This
parameter is optional. The default is No. The field can contain one of the
following values:
- Yes
- Specifies that the drives use WORM media.
- No
- Specifies that the drives do not use WORM media.
- FORMAT
- Specifies the recording format to be used when data is written to sequential
access media. This parameter is optional. The default value is DRIVE.
If the drives are in a library that includes drives of different tape technology, do not use the DRIVE value. Instead, specify the format that the drives use.
-
If you plan to upgrade all drives to Generation 4, 5, 6, 7, or 8, you must delete all existing LTO Ultrium drive definitions and the paths that are associated with them. Then, you can define the new Generation 4, 5, 6, 7, or 8 drives and paths.
-
LTO-8 drives are unable to read LTO-6 media. If you are mixing LTO-6 with LTO-8 drives and media in a single library, you must partition the library into two libraries. One library must have only LTO-8 drives and media and the other must have LTO-6 drives and media.
-
- ESTCAPacity
- Specifies the estimated capacity for the volumes that are assigned to this
device class. This parameter is optional.
You can specify this parameter if the default estimated capacity for the device class is inaccurate due to compression of data.
You must specify this value as an integer followed by one of the following unit indicators: K (kilobytes), M (megabytes), G (gigabytes), or T (terabytes). The smallest value that is accepted is 1 MB (ESTCAPACITY=1M).
For example, specify that the estimated capacity is 9 GB with the parameter ESTCAPACITY=9G.
- PREFIX
- Specifies the high-level qualifier of the data set name that the server writes into the
sequential access media labels. For each sequential access volume assigned to this device class, the
server uses this prefix to create the data set name. This parameter is optional. The default value
is ADSM. The maximum length of this prefix is 8 characters.
If you have a naming convention for media labels to support your current management system, use a volume prefix that conforms to your naming conventions.
Values that are specified for this parameter must meet the following conditions:- The value is to be made up of qualifiers, which can be a maximum of eight characters including
periods. For example, the following value is acceptable:
AB.CD2.E - The qualifiers must be separated by a single period.
- The first letter of each qualifier must be alphabetic or national (@,#,$), followed by alphabetic, national, hyphen, or numeric characters.
An example of a tape volume data set name using the default prefix is ADSM.BFS.
- The value is to be made up of qualifiers, which can be a maximum of eight characters including
periods. For example, the following value is acceptable:
- MOUNTRetention
- Specifies the number of minutes that an idle sequential access volume is retained before it is
dismounted. This parameter is optional. The default value is 60 minutes. You can specify a number 0
- 9999.
This parameter can improve response time for sequential access media mounts by leaving previously mounted volumes online.
However, for EXTERNAL library types (that is, a library that is managed by an external media management system), set this parameter to a low value (for example, two minutes) to enhance device sharing between applications.
Note: For environments in which devices are shared across storage applications, the MOUNTRETENTION setting must be carefully considered. This parameter determines how long an idle volume remains in a drive. Some media managers do not dismount an allocated drive to satisfy pending requests. You might need to tune this parameter to satisfy competing mount requests while maintaining optimal system performance. Typically, problems arise more frequently when the MOUNTRETENTION parameter is set to a value that is too small, for example, zero. - MOUNTWait
- Specifies the maximum number of minutes the server waits for an operator to respond to a request
to either mount a volume in a drive in a manual library or check in a volume to be mounted in an
automated library. This parameter is optional. If the mount request is not satisfied within the
specified amount of time, the mount request is canceled. The default value is 60 minutes. You can
specify a number 0 - 9999.Restriction: If the library that is associated with this device class is external (LIBTYPE=EXTERNAL), do not specify the MOUNTWAIT parameter.
- MOUNTLimit
- Specifies the maximum number of sequential access volumes that can be simultaneously mounted for
the device class. This parameter is optional. The default is DRIVES. You can specify a number 0 -
4096.
If you plan to use the simultaneous-write function, ensure that sufficient drives are available for the write operation. If the number of drives needed for a simultaneous-write operation is greater than the value of the MOUNTLIMIT parameter for a device class, the transaction fails.
The following are possible values:- DRIVES
- Specifies that every time a mount point is allocated, the number of drives that are defined and online in the library is used to calculate the true value.
- number
- Specifies the maximum number of drives in this device class that are used concurrently by the server. This value must never exceed the number of drives that are defined and online in the library that services this device class.
- 0 (zero)
- Specifies that no new transactions can gain access to the storage pool. Any current transactions continue and complete, but new transactions are terminated.
Example: Define an 8 mm device class
Define a device class that is named 8MMTAPE for an 8 mm device in a library named AUTO. The format is DRIVE, mount limit is 2, mount retention is 10, tape volume prefix is named ADSMVOL, and the estimated capacity is 6 GB.define devclass 8mmtape devtype=8mm library=auto
format=drive mountlimit=2 mountretention=10
prefix=adsmvol estcapacity=6G