Check OS:
 Free Space (file system)
 RAID Configuration
 Event logs
 Data, logfile and swap layout (looking at I/O contention)
 Patch levels

Database:
 Configuration
 Patch level
 Version

SAP:
 Check System log
 Check for failed updates
 Check response times
 Check Database Backup history
 Check Backup procedure
 Check for Program Dumps
 Check Spool error history
 Check R/3 buffer configuration