DASD Subsystem Exception

This report shows conditions that may need maintenance action. Records that are included in other reports may not be listed in the system exception reports.

This exception report can be used to determine if the DASD subsystem has excessive errors or is operating within acceptable limits.

This report is organized by probable failing unit (PFU) starting with the units closest to the processor (CPU) and working toward the volume. Within each section, the PFUs are ordered from most critical to least severe (or from the unit with the largest number of permanent errors to the unit with the smallest number of temporary errors).

The series contains the following types of reports:

TYPE	REPORT
1	DASD Subsystem Exception, Part 1
1	DASD Subsystem Exception, Part 2
2	DASD String Summary, Part 1 DASD String Summary helps you determine if a problem is unique to a particular device or is also occurring on other devices in the controller string.
2	DASD String Summary, Part 2
3	DASD Service Informational Messages (SIMs) Informational Messages help you define a problem to IBM customer service personnel.
3	DASD Informational Messages
4	DASD Data Transfer Summary Data Transfer is further broken down according to whether the PFU is the volume or something other than the volume.
5	DASD Symptom Code Summary Symptom Code lists the errors by fault symptom code within each probable failing unit (PFU) group.
6	DASD Storage Control Unit Summary Storage Control Unit (SCU) groups overruns under each interface between channel or subchannel and SCU.

These reports work together to provide a picture of the errors occurring in the system. The DASD subsystem exception report determines if your DASD subsystem is experiencing an excessive amount of errors.

The following table shows the type of error records and their source in the DASD subsystem exception reports:

TYPE	SOURCE
A3	DASD devices; including SCUs, controllers
MDR	DASD devices; including SCUs, controllers
OBR	DASD devices; including SCUs, controllers

A probable failing unit is identified through the physical ID of the device. The physical ID is the combined identifiers of storage controller, control unit, and device.

Note: You must code DASDID control statements to establish physical IDs for those DASD in your installation that do not provide their own physical IDs. That way, EREP recognizes units common to different systems and arrives at the correct PFUs.

Messages IFC264I and IFC265I are logged in the EREP messages (TOURIST) file for each invalid record. These records are not included in the system exception report and do not print device dependent information in other reports.

Valid records that do not indicate a need for maintenance action may be shown in reports other than the subsystem exception.

If errors are found, the necessary corrective action is shown on the next deeper level of DASD reports. See Figure 1 through Figure 1 and Direct-Access Storage Devices (DASD).

Figure 1 through Figure 1 show examples of the reports in the DASD subsystem exception series.