The IBM MVS System Logger is a component which provides a set of services for the writing, reading, and management of log streams. The majority of MVS System Logger functions execute in a separate address space named IXGLOGR on each member of the SYSPLEX.
A log stream is a chronologically ordered set of application specific data that is generally used for maintaining event histories, such as transaction and recovery logs. The MVS System Logger does not impose any particular structure or format of the data comprising an application log stream.
Examples of MVS system components that can be configured to use the MVS System Logger are LOGREC Recording and the MVS Operations Log (OPERLOG).
The major strengths and characteristics of the MVS System Logger services are:
The MVS System Logger supports two types of log streams:
An installation can use both types of log streams for various applications concurrently.
All log stream definitions and associated characteristics are contained in the LOGR Couple Data Set. This collection of information is generally referred to as Log Stream Policy Information. The LOGR couple data set must be accessible by all the systems in the SYSPLEX and is initially constructed and formatted by the IXCL1DSU utility. Policy information is maintained by executing the IXCMIAPU utility as well as through the IXGINVNT service.
CA SYSVIEW provides several commands which operate upon data contained in system log streams.
The OPERLOG command displays the contents of the MVS Operations Log. The data contained within this log stream is a superset of what is contained in the traditional MVS SYSLOG. An installation can choose to use either or both of these message logging facilities. If the OPERLOG is to be used, it must be named SYSPLEX.OPERLOG and can be either Coupling Facility or DASD Only based. When using a coupling facility based OPERLOG, the information from the participating members of the SYSPLEX is logically merged by the MVS System Logger into a single chronologically ordered log stream.
The LOGREC command displays the contents of the MVS error recording log. The traditional location of this information is the SYS1.LOGREC data set. Much like the Operations Log, the installation can choose to collect the error recording log data in an MVS System Logger log stream instead of the SYS1.LOGREC data set. This log stream can be either coupling facility or DASD only based.
The following IBM publications contain detailed information about the MVS System Logger as well as the processes the installation must follow to exploit the MVS System Logger for the Operations Log and Error Recording facilities:
GA32-0905 z/OS Diagnosis: Tools and Service Aids
SA23-1390 z/OS MVS Planning: Operations
SA23-1368 z/OS MVS Programming: Assembler ServicesGuide
SA23-1371 z/OS MVS Programming: Authorized AssemblerServices Guide
SA23-1399 z/OS MVS Setting Up a Sysplex