Transient Data

Transient data costs in this section are for the following:

Intrapartition Queues

The approximations for non-recoverable and logically recoverable intrapartition TD queues do not include any VSAM I/O cost. A VSAM I/O costs approximately 11.5K and occurs:

Non-Recoverable TD Queue

WRITEQ READQ DELETEQ
1.5 1.3 1.3

Logically Recoverable TD Queue

WRITEQ READQ DELETEQ
First: 2.8 Subsequent:1.5 First: 2.4 Subsequent:1.4 1.1

Notes:

The main difference between Non-Recoverable and Logically Recoverable TD Queues occurs at Syncpoint time. At syncpoint, the new TD Queue addresses are put in the Log Buffer and a forced Log write is requested. The cost to put the data in the buffer is about 2.0K. The cost of writing the Log Buffer to the CF is described in the section on Recovery Costs.

Physically Recoverable TD Queue

WRITEQ READQ DELETEQ
19.7 First: 9.3 Subsequent:8.8 8.7
Notes:

Physically Recoverable WRITEQ requests involve forcing a VSAM I/O and forcing a Log write to the CF for every request.

Extrapartition queues

The approximate calculations for extrapartition TD queues do not include any I/O cost. An I/O for a physically sequential file costs approximately 7.0K and occurs as follows:

Therefore, under certain circumstances, a READQ could incur the cost of two I/Os.

Extrapartition TD queues are non-recoverable.

WRITEQ READQ
1.2 1.0
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