Message History 
The Kernel user menu contains a display of the log files that are backed up when the database crashes, as well as the kernel message history.
Normally, at least the kernel log knldiag, the database trace log knltrace, and the memory dump rtedump are backed up if the database crashes. These files are in a subdirectory of the directory diaghistory, where they can be used for diagnoses.
Procedure
Open the Database Assistant (transaction DB50) or the liveCache Assistant (transaction LC10). Choose 
Problem Analysis 
Messages Kernel History 
.
The messages display is a component of the DBA Cockpit and can therefore also be called as follows:
Open DBA Cockpit (transaction DBACOCKPIT).
The display options in DBA Cockpit vary depending on which SAP NetWeaver release you are using.
Choose
Diagnosis Messages Kernel Messages: History ..SAP NetWeaver 7.1: Choose
Diagnosis Kernel Messages History .
Result
The existing subdirectories of the diaghistory directory are displayed, sorted according to the time your backup was performed.
The available kernel message history (KnlMsg_<time_stamp> files) is displayed. You can open and analyze any of the log files.