UPDATE DEVCLASS (Update an LTO device class)
Use the LTO device class when you are using LTO tape devices.
Privilege class
To issue this command, you must have system privilege or unrestricted storage privilege.
Syntax
- 1 IBM Spectrum® Protect server supports LTO-2 tape drives; however, IBM® Tape Device drivers do not. In the event of an issue with the LTO-2 drive, the preferred corrective action is to upgrade your tape drive hardware to a higher generation drive, then install the latest version of the device driver.
- 2 You cannot specify DRIVEENCRYPTION=ON if your drives are using WORM (write once, read many) media.
- 3 Drive encryption is supported only for LTO-4 and higher generation LTO drives and media.
Parameters
- device_class_name (Required)
- Specifies the name of the device class to be updated. The maximum length of the device class name is 30 characters.
- LIBRary
- Specifies the name of the defined library object that contains the LTO tape drives used by this device class. For information about defining a library object, see the DEFINE LIBRARY command.
- 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 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: Restrictions apply to logical block protection (LBP):- At the LTO-5 level, LBP is supported only on IBM LTO-5.
- Starting with LTO-6, LBP is supported on all LTO drives.
- FORMAT
- Specifies the recording format to be used when data is written to sequential
access media. This parameter is optional.
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.
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If you plan to upgrade all drives to Generation 4, 5, 6, 7, 8you 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, drives and paths.
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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.
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- ESTCAPacity
Specifies the estimated capacity for the sequential access volumes that are categorized by 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.
To force the IBM Spectrum Protect server to determine the estimated capacity for the volumes that are assigned to this device class, specify ESTCAPACITY="".
- 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 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. 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. 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. 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. Drive
encryption is supported only for LTO-4 and higher
generation drives and media.Restriction: If encryption is enabled for a device class, and the device class is associated with a storage pool, the storage pool should not share a scratch pool with other device classes that cannot be encrypted. If a tape is encrypted, and you plan to use it on a drive that cannot be encrypted, you must manually relabel the tape before it can be used on that drive.
- 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 are not encrypted. For example, back up sets, export volumes, and database backup volumes are not encrypted.) If you specify ON and you enable another 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 another 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. When you specify EXTERNAL and IBM Spectrum Protect detects that AME encryption is enabled, IBM Spectrum Protect does not turn off encryption. By contrast, when you specify ALLOW and IBM Spectrum Protect detects that AME encryption is enabled, IBM Spectrum Protect turns off encryption.
- OFF
- Specifies that drive encryption is not allowed. If you enable another method of encryption, backups fail. If you enable the application method, IBM Spectrum Protect disables encryption and backups are attempted.
Example: Update the mount limit for an LTO device class
Update a device class named LTOTAPE. Change the mount limit to 2.update devclass ltotape mountlimit=2