This section describes the Computing Center Management System (CCMS) from the high availability perspective. The CCMS lets you monitor, control, and configure your SAP system. It lets you automate many administrative tasks, so reducing the chances of error and enabling in many cases unattended, 24-hour system management from within the SAP system. Therefore, it is well suited to maintaining high availability of your system.
The CCMS provides the following functions relevant to achieving high availability:
· Comprehensive monitoring and management
This helps to avoid downtime, since a poorly managed system is more likely to fail. With the new monitoring architecture – available since SAP Release 4.0 – you can monitor components within and external to the SAP system. Alerts are triggered when the values reported to the monitoring architecture conflict with predefined thresholds. Alerts can be handled automatically by the system or manually by the operator.
All information relevant to troubleshooting a particular problem is available from a single, central point. This is the major advantage of the monitoring architecture. Having an overview of the SAP system reduces errors – possibly leading to system downtime – that might otherwise arise from using multiple tools. You can also extend the monitor and alert infrastructures for special purposes by using the standard programming interface to incorporate external tools.
· Reconfiguration during 24-hour system operation
You can configure instances and specify operation modes to suit the varying conditions and workloads in your system. For example, during the day you can assign the majority of work processes to dialog processing, whereas at night you can assign them to background processing. Switching between, for example, daytime and nighttime processing mode does not cause downtime of the SAP system.
· Profile maintenance
For tuning the configuration of SAP servers, the CCMS also offers the profile maintenance tool, with which you can track and check the consistency of your changes to start-up and system profiles. Therefore, you can avoid downtime due to a poorly tuned system.
· Graphical control tools
The CCMS has easy-to-use control tools with both graphical and list-oriented displays. You can use these tools for administrative tasks such as starting or stopping servers, viewing logs, and checking user and work process activity. Fewer errors are made using modern graphical tools, so avoiding unnecessary downtime.
· System and business process statistics
The CCMS can collect detailed statistics for tracking system activity and application-related business process activity. These statistics are useful for assessing the current workload or for predicting the future workload, so avoiding downtime due to severe performance bottlenecks or lack of space in database objects.
· Database and archiving management
Many database administration tasks can be performed from within the SAP system using the CCMS. For example, you can use the DBA Planning Calendar to schedule and analyze the results of database administration activities. A database monitor is provided for in-depth analysis of the database. These tools help you to better manage the database, so reducing downtime.
Data archiving ensures that the online part of the SAP system is small and therefore easy to manage, while still allowing access to the entire data for reporting and other purposes. The Archive Development Kit (ADK) allows you to develop your own archive programs.
In the area of database monitoring and tuning, some of the functions of the CCMS are duplicated by the database-specific administration tools (such as BR*Tools for Oracle). It is not possible to give strict guidelines for when to use the database administration tools and when to use the CCMS. The characteristics of your installation and the nature of the problem or requirement determine the best tool to use. However, in general, use the CCMS to automate routine tasks where possible and a database-specific administration tool for other tasks (for example, when the SAP system is down).
· Workload management
Reliable workload management means that you can successfully coordinate large amounts of system load without running into severe performance bottlenecks, which can in some cases amount to downtime. The CCMS provides the following features to help you with this:
Ў SAP background processing
This feature allows you to run programs asynchronously with step-by-step control. Various types of scheduling are available and you can schedule your own background jobs under program control using the easy-to-use application program interface (API). A variety of features are provided to make managing even large background jobs easy.
Ў Load Balancing
The available workload is balanced by the CCMS in the following areas:
§ Logon load balancing distributes interactive users across available servers at logon time.
§ Output workload balancing in the spool system distributes job output across available spool servers and pooled output devices.
§ Background processing balancing distributes background jobs across available background servers.
SAP recommends the following when you use the CCMS to reduce downtime:
· Define operation modes for 24-hour operations
You can use the CCMS to define different operation modes (for example, a night-time and a daytime mode). Using operation modes avoids the need for system downtime to reconfigure the system.
· Monitor your system for problems
The CCMS provides you with the opportunity to monitor many different aspects of your system. Get to know these possibilities since, apart from the performance gains, you can also benefit by analyzing trends and spotting difficulties (such as system bottlenecks) before they turn into real problems. The advantage for system availability is that you can then schedule preventive maintenance and upgrades as planned downtime rather than being forced into unplanned downtime.
· Use alerts
Use the CCMS monitoring architecture to check the health of your system regularly. The following is a list of resources that can cause or increase downtime if a red alert appears:
Ў Swap space (an operating system parameter)
Ў File system (an operating system parameter)
Ў Enqueue table capacity (an SAP system parameter)
Ў Freespace management, including extent allocation problems (a database system parameter)
Ў Elapse time since last backup (a database system parameter)
· Do not adjust alert thresholds
Predefined thresholds are set for a specific system that you are monitoring. Only adjust the values for these thresholds if you are sure that the change is necessary and will bring the required result.
· Use a database-specific administration tool with the CCMS for database administration
CCMS and database-specific administration tools have different strengths and weaknesses. In general, SAP recommends you to use the CCMS for routine database administration, and a database-specific administration tool to perform any additional analyses or tasks not supported by CCMS (such as altering the database structure).
· Use the DBA Planning Calendar to schedule database activities
Depending on your database, various routine database management activities can be run regularly from the DBA Planning Calendar, such as backups, updating the cost-based optimizer (CBO) statistics, configuration and performance checks, and so on. Of course, you must still satisfy external requirements for the activity, such as tapes and tape devices for backups. You can check the job log produced by the CCMS to see if the activity completed successfully.
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