Like pubsets, large volumes have their own attribute: LARGE_VOLUME.
The LARGE_VOLUME attribute characterizes a logical volume and indicates that the volume has a gross capacity >= 32 GB.
The LARGE_VOLUME attribute is stored in the base record of the SVL when the volume is initialized with VOLIN.
Just as the LARGE_OBJECTS characteristic is for pubsets, the LARGE_VOLUME characteristic is permanent and is stored in the SVL.
Restrictions for large volumes
Large volumes can only be added to LARGE_OBJECTS pubsets.
VOLIN
VOLIN supports a maximum capacity of 2 TB for any formatting.Large volumes are not allowed as private disks. Any attempt to initialize a large volume as a private disk will be rejected with the following error message:
NVL0146 DISK CAPACITY GREATER EQUAL 32GB IS NOT PERMITTED FOR PRIVATE DISKS
Volume management interface affected by 32-GB objects
Interface | Change |
Privileged utilities | |
SIR | Installing and extending pubsets, initializing volumes in respect of LARGE_OBJECTS |
High-performance support of large volumes
If the load on the volume increases in accordance with the larger amount of data when large volumes are used, provisions should be made to ensure high-performance support:
External disk storage subsystems which employ the RAID hard disk system can be employed to increase performance (and to enhance data security).
When large volumes are used, RAID 5, RAID 6 or preferably RAID 1/0 is recommended. In this case the data of a logical volume is distributed over multiple physical disks (striping).In addition, use of the BS2000 function PAV (Parallel Access Volume) on /390 servers in order to parallelize the disk inputs/outputs. On x86 servers the corresponding function using RSC for disk I/Os is available by default.
Combining both measures results in considerable enhancements in TP and batch operation (in the case of multitask batch), in terms of both the I/O times and the throughput. Also refer to the “Performance Handbook” [12].