Tape capacity considerations
Any IBM tape device supported by your operating system can be used for work space. However, using tape devices for work data sets rather than disk causes significant performance degradation and should, therefore, be avoided.
Three different tape work data set techniques are available to DFSORT: Balanced, Polyphase, and Oscillating. For information on how to calculate their requirements, see Table 1.
Note: The value you obtain for "min" is literally a
minimum value; if, for example, your input uses a more efficient blocking
factor than DFSORT or is spanned, you need more work space. Space
requirements are also summarized in Table 1. DFSORT selects
the most appropriate tape technique using these criteria.
Work Space Requirements of the Various Tape TechniquesTape Technique
|
Maximum Input | Work Space Areas Required | Max. No. of Work Areas | Comments |
---|---|---|---|---|
Balanced tape (BALN) | 15 volumes | Min=2(V+1)* tape units | 32 volumes | Used if more than three work storage tapes are provided and file size is not given. |
Polyphase tape (POLY) | 1 volume | Min=3 tape units | 17 volumes | Used if three work storage tapes are provided. |
Oscillating tape (OSCL) | 15 volumes | Min=V+2* or 4 tape units, whichever is greater | 17 volumes | File size must be given. The tape drive containing SORTIN cannot be used as a work unit. |
Note:
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