Service Failure

This section describes how to detect failure in the SAP system services, what the effects of failure are, and how to recover from failure of SAP services.

Note Note

The SAP service processes can fail due to any of the common causes outlined Standard Failures in System Failure (SAP NetWeaver AS).

End of the note.

SAP System Service Failures: Front End, Dispatcher, Dialog, Update, and Enqueue
Failure	Detection	Effects	Recovery
Front End	By the user and dispatcher	The sessions of one user are aborted	Manual restart Front-end reconnect can be used
Dispatcher	No automatic detection (except service manager on Windows)	Application service fails, all users are logged out If dispatcher is on enqueue host (and enqueue is not replicated), then entire SAP system affected	Manual restart or switchover of application service
Dialog (ABAP)	By the dispatcher A Syslog entry is created	User session of one user can be aborted	Automatic restart by the system
Update (ABAP)	By the dispatcher A Syslog entry is created	Possibly one aborted update	Automatic restart by the system
Enqueue	By the dispatcher A Syslog entry is created	Temporarily not possible to obtain enqueues from application hosts	If enqueue host is restarted manually, transactions on other application hosts are automatically restarted A replicated enqueue recovers all transactions

SAP System Service Failures: Background, Message, Gateway, Internet Communication Manager (ICM), Spool, Database, and Java Message Service
Failure	Detection	Effects	Recovery
Background (ABAP)	By the dispatcher Syslog and joblog entries are created	A single batch job might fail	Automatic restart of WP by dispatcher
Message	By the dispatchers on all application hosts A Syslog entry is created	Until message service is restarted, the entire SAP System is affected (for example, requests cannot be executed for dialog, update & enqueue hosts)	By the ABAP dispatcher on all ABAPapplication servers By the Java instance controller on all Java application servers
Gateway (ABAP)	By the dispatcher A Syslog entry is created	Temporarily no RFC and other external communications possible	Automatic restart of WP by dispatcher
Internet Communication Manager	By the dispatcher A Syslog entry is created	Temporarily requests cannot be handled (for example, http, https, smtp)	Automatic restart of ICM by dispatcher
Spool (ABAP)	By the dispatcher Syslog entries are created	A single print job fails Failed print job restarted	Automatic restart of WP by dispatcher
Database	No automatic detection Syslog entries show database errors	Entire SAP System is affected No SQL requests to database arepossible	Manual restart (and recovery if necessary) of database
Java Message Service	Detection	JMS messages temporarily cannot be sent	Manual recovery

Note Note

Consider using Switchover Software

You can use switchover software for the database host and the application host on which the enqueue and message services are running. Automatic failure detection and automatic restart (on a standby host) are thereby ensured.

For more information about using switchover to protect the enqueue service, see Replicated Enqueue Server.

End of the note.