DEFINE DEVCLASS (Define an 8MM device class)

Privilege class

To issue this command, you must have system privilege or unrestricted storage privilege.

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.

Note: If you select Yes, the only options available for the FORMAT parameter are:

• DRIVE
• AIT
• AITC

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. Use the specific format that the drives use.

The following table lists the recording formats and estimated capacities for 8 mm devices:

Table 1. Recording format and default estimated capacity for 8 mm tape

Format    Medium Type	Estimated Capacity	Description
DRIVE	–	The server selects the highest format that is supported by the drive on which a volume is mounted. Attention: Avoid specifying DRIVE when a mixture of drives is used within the same library. For example, do not use this option for a library that contains some drives that support recording formats superior to other drives.
8200	2.3 GB	Uncompressed (standard) format, using standard 112-meter tape cartridges
8200C	See note 3.5 GB 4.6 GB	Compressed format, using standard 112-meter tape cartridges
8500    15m    15m    15m    54m    54m    54m    112m    112m    112m    160m XL	See note 600 MB 600 MB 600 MB 2.35 GB 2.35 GB 2.35 GB 5 GB or 10.0 GB 5 GB or 10.0 GB 5 GB or 10.0 GB 7 GB	Drives (Read Write) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW)
8500C    15m    15m    15m    54m    54m    54m    112m    112m    112m    160m XL	See note 1.2 GB 1.2 GB 1.2 GB 4.7 GB 4.7 GB 4.7 GB 5 GB or 10.0 GB 5 GB or 10.0 GB 5 GB or 10.0 GB 7 GB	Drives (Read Write) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW) Exabyte 8500/8500C (RW) Exabyte 8505 (RW) Eliant 820 (RW)
8900    15m    54m    112m    160m XL    22m    125m    170m	See note – – – – 2.5 GB – 40 GB	Drive (Read Write) Mammoth 8900 (R) Mammoth 8900 (R) Mammoth 8900 (R) Mammoth 8900 (R) Mammoth 8900 (RW) Mammoth 8900 (RW with upgrade) Mammoth 8900 (RW)
AIT    SDX1–25C    SDX1–35C    SDX2–36C    SDX2–50C    SDX3–100C    SDX3X-150C    SDX4–200C    SDX5-400C	See note 25 GB 35 GB 36 GB 50 GB 100 GB 150 GB 200 GB 400 GB	Drive AIT, AIT2 and AIT3 drives AIT, AIT2 and AIT3 drives AIT2 and AIT3 drives AIT2 and AIT3 drives AIT3, AIT4, and AIT5 drives AIT3-Ex, AIT4, and AIT5 drives AIT4 and AIT5 drives AIT5 drive
AITC    SDX1–25C    SDX1–35C    SDX2–36C    SDX2–50C    SDX3–100C    SDX3X-150C    SDX4–200C    SDX5-400C	See note 50 GB 91 GB 72 GB 130 GB 260 GB 390 GB 520 GB 1040 GB	Drive AIT, AIT2 and AIT3 drives AIT, AIT2 and AIT3 drives AIT2 and AIT3 drives AIT2 and AIT3 drives AIT3, AIT4, and AIT5 drives AIT3-Ex, AIT4, and AIT5 drives AIT4 and AIT5 drives AIT5 drive
M2    75m    150m    225m	See note 20.0 GB 40.0 GB 60.0 GB	Drive (Read Write) Mammoth II (RW) Mammoth II (RW) Mammoth II (RW)
M2C    75m    150m    225m	See note 50.0 GB 100.0 GB 150.0 GB	Drive (Read Write) Mammoth II (RW) Mammoth II (RW) Mammoth II (RW)
SAIT	See note 500 GB	Drive (Read Write) Sony SAIT1–500(RW)
SAITC	See note 1300 GB (1.3 TB)	Drive (Read Write) Sony SAIT1–500(RW)
VXA2    V6 (62m)    V10 (124m)    V17 (170m)	See note 20 GB 40 GB 60 GB	Drive (Read Write) VXA–2
VXA2C    V6 (62m)    V10 (124m)    V17 (170m)	See note 40 GB 80 GB 120 GB	Drive (Read Write) VXA–2
VXA3    X6 (62m)    X10 (124m)    X23 (230m)	See note 40 GB 86 GB 160 GB	Drive (Read Write) VXA–3
VXA3C    X6 (62m)    X10 (124m)    X23 (230m)	See note 80 GB 172 GB 320 GB	Drive (Read Write) VXA–3
Note: The actual capacities might vary depending on which cartridges and drives are used. For the M2C format, the normal compression ratio is 2.5:1. For the AITC and SAITC formats, the normal compression ratio is 2.6:1.

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.

For more information about the default estimated capacity for 8 mm tapes, see Table 1.

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.

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.

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.

Note: For EXTERNAL library types, do not specify DRIVES for the MOUNTLIMIT value. Specify the number of drives for the library as the MOUNTLIMIT 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.