Upon start-up, Adaptive Server begins to write information to a local error log file: %SYBASE%\%SYBASE_ASE%\install\errorlog.
Use sp_errorlog to dynamically change its path. Once the older error log is not being used by Adaptive Server, you can move it, and make space available.
See Diagnosing System Problems in the System Administrator Guide, Volume 1 for a description of the error log format.
Logging to the Adaptive Server error log is always enabled. However, when you create or modify a specific user-defined message, you can set it to be omitted from the log.