SAP SM21

It displays the SAP system log, time-stamped records of system events, errors and warnings per instance, a primary tool for diagnosing system-level problems.

• Time/date and instance selection.
• Log entries with type and message.
• Details of each entry (cause, context).
• Filtering by user/transaction/problem class.

• Correlate log entries with the time of a reported problem.
• Look for database, work-process and configuration errors.
• Combine with ST22 (dumps) and SM13 (updates) for a full picture.

• Database connection/lock issues logged.
• Work-process errors or restarts.
• Not correlating by time (missing the relevant entries).

• Reading one instance. A multi instance system logs per instance, so the entry you want may be on an application server you did not select.
• Reading the times as the user's time zone. The log records system time, and an hour's difference is enough to miss the entry entirely.
• Treating every warning as an incident. The log is noisy by design, and the skill is recognising which entries are normal for your system.
• Selecting a narrow window around the reported time. The cause frequently precedes the symptom by minutes.
• Stopping here. The system log says something failed; the dump analysis and the update records usually say why.