Data sources

RMF records 74 subtype 5

RMF records 74 subtype 5 provide information about cache operations. While these records are created on individual z/OS systems, information in them is obtained by RMF by querying cache controllers. So the results in a particular interval are the same, no matter what system issued the query. So, it is sufficient to collect (or process) these records only on the system (or a few systems), which has access to all DASD volumes in the data center. RMF type 74 subtype 5 records also provide another vital piece of information. They provide the connection between individual DASD volumes and hardware storage subsystems, cache controllers, RAID boxes and so on.

RMF records 78 subtype 3

RMF record 78 subtype 3 provide information about channel usage by logical control units.

DCOLLECT volume records

DCOLLECT volume records provide information about free and used space.

DCOLLECT is a utility that runs in batch mode and stores the space information in a sequential file. Because space usage information is usually used for long-term capacity planning, UIE creates only one set of space usage metrics for each run. In Visualizer, this information can be summarized over weeks, months, quarters, and so on.

When using DCOLLECT, you have two options:

• You can run DCOLLECT as an independent job, store its results in a DASD file, and provide this file name to UIE.
• You can request that the UIE front end create the DCOLLECT step as part of UIE job. In this case, DCOLLECT results are stored in a temporary file, which is passed to the UIE step and is deleted after the UIE job ends.

UIE obtains all storage information from the four preceding sources. If any information in these sources is missing or invalid, the accuracy of the UIE results will be affected. For example:

• If some volume space information is not included in the DCOLLECT file, this information is not counted in free and used space for the storage subsystem. The two most common cases in which this happens are as follows:
  • Devices are not online on the system where DCOLLECT runs. In this case, it is possible to run DCOLLECT on several systems and concatenate their resulting files.
  • Devices are used by a program that does not permit DCOLLECT to read VTOC information.
• If RMF data from some z/OS images that use particular volumes were not supplied to UIE, storage subsystem logical views (that is, activity of these individual z/OS images) are not represented by UIE. However, the cache activity data includes activity of all systems, which might cause a big disparity between cache activity numbers and logical view activity numbers.
• If information about some devices is not included in type 74/5 records, it is impossible to connect these devices with a particular storage subsystem. All such devices are associated with artificial storage subsystem with a serial number 00000000. The most common cases of such devices are as follows:
  • Devices that are offline on the system where type 74/5 were collected
  • Mirror image devices
  • Remote copy devices