Online Log Viewer 
Use
You can view logs and traces online with the integrated Log Viewer which runs in the SAP Web AS Java inside the Visual Administrator. Each time a new log is created the log server is informed. The Log Viewer client accesses the logs available on the SAP Web AS Java. No separate configuration is required.
If the SAP Web AS Java is down, no log files are accessible.
For support, each host must be accessible by application sharing tool.
Archive Logs
You can also view archive logs with the Online Log Viewer. Archive logs are old logs that are compressed (zipped up) to save disk spaces. By default, logs are written to a maximum of five files with 10MB capacity of each file. Thus, when this set of five files are full, it will rotate back to the first file and start overwriting the old logs. Before overwriting the old logs, the Log Configurator service backs up the five files into a zip file. So, each zip file contains a set of five log files. The logs within these zip files are called archive logs.
See also: