Placing Certain Control-M/IOA Files on Special Disk Devices

Some sites have special disk devices such as

• solid state (semiconductor) disk devices
• disks with fixed heads
• disk controllers with cache memory

Several Control‑M/IOA files are good candidates for placement on these devices.

The (usually temporary) file referenced by DD statement OUT180 is a good example. The first three SYSOUT files of a job submitted by Control‑M are read from spool and written to this file for later analysis. A permanent file can be allocated on an appropriate device and defined in DD statement OUT180 to control the placement of this file.

This file is obsolete if Control‑M/Restart has been installed.

In DD statement OUT180, some customers specify UNIT=VIO (that is, Virtual I/O) to gain I/O performance improvement through the MVS paging mechanism. You should measure your system’s paging performance before considering this.

• active Jobs File (AJF)
• IOA Conditions File (CND)
• Control‑M Resources File (RES)
• IOA Log File
  • If disks with fixed heads are available (for example, 3350 disks with fixed-heads, or equivalent), it may be advantageous to place the first track of the Active Jobs file, and/or the first track of the IOA Log file under the fixed-head areas. The first block of the file contains frequently accessed data and pointers that enable direct access to the respective files.
  • If solid-state semiconductor devices are available, it may be advantageous to place the OUT180 file and/or the RES file on them. Other files can also be considered, depending on the capacity of the devices.
  • If disk controllers with cache memory are available, it may be advantageous to place active Control‑M/IOA files on disk packs connected to such controllers. We suggest performing tests in order to determine whether the hit rate observed at your site justifies implementing this recommendation. These tests must be performed after choosing the optimal sleeping interval. For more information, see Choose an Appropriate Sleeping Interval.

All of these suggestions have a positive impact on the performance of the Control‑M monitor and other Control‑M components. They also minimize the likelihood of two Control‑M components attempting to access the same resource at the same time.

These suggestions also have a positive impact on the performance of some IOA Online facility screens. For example, optimizing Active Jobs file placement speeds up performance when using Screen 3 of the Online facility. Optimizing IOA Log file placement speeds up performance when using the Screens 5 and 3.L of the Online facility.