Modifying the data set support options

You can also modify the DATASET options while the data gatherer is active through the MODIFY session command. For more information, see Modifying RMF session options.

Example:

Assume you have started data set recording and have already defined data sets RMF™.DS01 through RMF.DS05. Data sets RMF.DS01, RMF.DS02, RMF.DS03, and RMF.DS05 are full. RMF.DS01 contains the oldest data and RMF.DS04 is currently active.

You want to:

  1. Save the data on RMF.DS04
  2. Switch the current writing of the sampled data to another data set
  3. Change the WHOLD value from the default of 7 to 5 megabytes.
The following command modifies the options: 
MODIFY  RMF,MODIFY III,DS(SWITCH),DS(DEL(RMF.DS04)),DS(WHOLD(5))
  1. The DEL suboption prevents RMF from overwriting data on RMF.DS04. RMF can no longer use RMF.DS04 for data set recording so the existing data is saved.
  2. SWITCH causes RMF to begin writing in another data set. Because there is no empty data set, RMF chooses the data set with the oldest data, in this case RMF.DS01, and begins writing over the old data in it.
  3. The WHOLD value lets RMF hold a copy in its buffer of five megabytes of storage containing data already copied to the data set. After it exceeds the value, it begins to page release the storage in the buffer containing the duplicate data.
Parent topic: Description of Monitor III data gatherer options