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The following is a step by step example of preparing for a large load that includes secondaries. The procedure for S6BBRSIX is almost identical, except that the input data comes from a table rather than a file, and therefore the amount of work file space required is slightly less than would be required for a load.A variable block data set containing approximately 150 million records is loaded to the table ATABLE, located on segment 1. This table:
With the default work data set block size at 4096 (actually 4067) space is required for over three million blocks of primary space on one disk volume, “UNIT WORKV, 01”.By obtaining the optimum block size or just under a half track for a fixed block data set with a record length of 83, the space required is minimized and sorting is optimized.Using either menu option 3.2 of ISPF or program IEFBR14, allocate a dummy data set with the characteristics of the work data set: FB UNIT=WORKV LRECL=83, specifying a block size of zero. The system calculates the optimum block size for that data set on that UNIT (WORKV).
The load requires 445113 blocks (222557 tracks) of space for the work data set. One volume of this example’s UNIT “WORKV” contains 50000 tracks, so the load requires four and a half volumes of disk space for the work file.The load always requests the total space required as the primary allocation. Therefore, it is necessary to modify the S control record so that the calculation results in a primary (and secondaries = 75% of primary) allocation suited to the space available.There are 7 volumes in the WORKV UNIT group; one volume is completely empty and is used for the primary allocation (approximately 100000 blocks). The remaining six volumes contain sufficient contiguous space to satisfy the secondary allocations (approximately 7 x 50000 blocks).
Be careful not to specify more volumes than actually exist in the chosen UNIT. If you do, the job aborts.
Before submitting the load, check that the work file space is available when required. Since the primary allocation is not sufficient to finish the load, the job could abort due to lack of space after wasting a considerable amount of resources as well as elapsed time.
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Copyright © TIBCO Software Inc. All Rights Reserved |