DEFINE DEVCLASS (Define a 3592 device class)
Use the 3592 device class when you are using 3592 tape devices.
If you are defining a device class
for devices that are to be accessed through a z/OS® media
server,
see DEFINE DEVCLASS (Define a 3592 device class for z/OS media server).
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 tape drives that can be used by this device class.
For information about defining a library object, see the DEFINE LIBRARY command.
- DEVType=3592 (Required)
- Specifies that the 3592 device type is assigned to the device class.
- LBProtect
-
Specifies whether logical block protection is used to ensure the integrity of data stored on tape. When LBPROTECT is set to READWRITE or to WRITEONLY, the server uses this feature of the tape drive for logical block protection and generates cyclic redundancy check (CRC) protection information for each data block written on tape. The server also validates the CRC protection information when data is read from the tape.
The default is NO.
The following values are possible:- READWrite
- Specifies that logical block protection is enabled in the server and the tape drive for both
read and write operations. Data is stored with CRC information in each block. This mode affects
performance because additional processor usage is required for IBM Spectrum® Protect and the tape drive to calculate and compare CRC
values. The READWRITE value does not affect backup sets and data that is generated by the
BACKUP DB command.
When the LBPROTECT parameter is set to READWRITE, you do not have to specify the CRCDATA parameter in a storage pool definition because logical block protection provides better protection against data corruption.
- WRITEOnly
- Specifies that logical block protection is enabled in the server and the tape drive for write operations only. Data is stored containing CRC information in each block. For read operations, the server and the tape drive do not validate the CRC. This mode affects performance because additional processor usage is required for IBM Spectrum Protect to generate the CRC and for the tape drive to calculate and compare CRC values for write operations. The WRITEONLY value does not affect backup sets and data that are generated by the BACKUP DB command.
- No
- Specifies that logical block protection is not enabled in the server and the tape drive for read and write operations. However, the server enables logical block protection on write operations for a filling volume that already has data with logical block protection.
Restriction: Logical block protection is supported only on IBM® 3592 Generation 3 drives and later with 3592 Generation 2 media and later.For an explanation about when to use the LBProtect parameter, see technote 490283.
- 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.
- SCALECAPacity
- Specifies the percentage of the media capacity that can be used
to store data. This parameter is optional. The default is 100. Possible
values are 20, 90, or 100.
Setting the scale capacity percentage to 100 provides maximum storage capacity. Setting it to 20 provides fastest access time.
Note: The scale capacity value takes effect only when data is first written to a volume. Any updates to the device class for scale capacity do not affect volumes that already have data that is written to them until the volume is returned to scratch status. - 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, 8, or 9, 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, 8, or 9drives 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.
-
LTO-9 drives are unable to read Ultrium 7 and Ultrium M8 media. If you are mixing LTO-7 with LTO-9 drives and media in a single library, you must partition the library into two libraries. One library must have only LTO-9 drives and media and the other must have LTO-7 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, setting this parameter to a low value (for example, two minutes) enhances 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.
- DRIVEEncryption
- Specifies whether drive encryption is allowed. This parameter
is optional. The default is ALLOW.
- ON
- Specifies that IBM Spectrum Protect is the key manager for drive encryption and allows drive encryption for empty storage pool volumes only if the application method is enabled. (Other types of volumes-for example, back up sets, export volumes, and database backup volumes-will not be encrypted.) If you specify ON and you enable either the library or system method of encryption, drive encryption is not allowed and backup operations fail.
- ALLOW
- Specifies that IBM Spectrum Protect does not manage the keys for drive encryption. However, drive encryption for empty volumes is allowed if either the library or system method of encryption is enabled.
- EXTERNAL
- Specifies that IBM Spectrum Protect does not manage the keys for drive encryption. Use this setting with an encryption methodology that is provided by another vendor and that is used with Application Method Encryption (AME) enabled on the drive.
- OFF
- Specifies that drive encryption is not allowed. If you enable either the library or system method of encryption, backups fail. If you enable the application method, IBM Spectrum Protect disables encryption and backups are attempted.