Guy Glantser has some tips for managing the SQL Server error log:
SQL Server maintains its own log, also called “SQL Server Error Log”. This log contains messages describing informational and error events, similar to messages that you can find in Windows logs. In fact, many of the messages found in the SQL Server Error Log can also be found in the Windows Application Log. The SQL Server Error Log is a great place to find information about what’s happening on your database server.
SQL Server uses 7 log files to store these messages. One file serves as the current log file, and every new message is written to that file. The other 6 files are archived files, and they contain previous messages. Each time SQL Server is restarted, it recycles the files. What does it mean? First, it means that a new log file is created and becomes the new current log file. Second, the oldest log file (“Archive #6”) is deleted. And third, all the other log files are pushed back one step. The previous current log file becomes “Archive #1”, the previous “Archive #1” log file becomes “Archive #2”, and so on.
Read on to see how you can change this, manage the size of log files, and retain data for a longer time.