eG Monitoring
 

Measures reported by WDispCacheTest

The SAP Web dispatcher can be configured in such a way that the contents (static and dynamic) are stored in the cache, and the next request to this page can be satisfied quickly from the cache. The SAP Web dispatcher normally forwards incoming requests to an Internet Communication Manager (ICM), which is responsible for Web requests in SAP NetWeaver AS. The advantage of caching in the Web dispatcher over caching in the ICM is that the cache is located at the initial access point where all the requests arrive, and therefore all backend servers activated later and their network connections are offloaded. Caching is deactivated in the SAP Web Dispatcher by default. You need to activate caching by specifying a URL prefix and cache directory in the parameter icm/HTTP/server_cache_0 in the Web Dispatcher profile with which the SAP Web Dispatcher was started.

This test monitors the cache of the SAP Web Dispatcher and reports the total size of all cache entries, the total number of cache entries etc. Using this test, administrators can easily detect the number of invalid entries and remove them from the cache. This way, administrators can analyze how quickly the cache processes the requests. In the process, the test points to poor cache usage and processing bottlenecks, and reveals if the cache is poorly sized.

Outputs of the test : One set of results for the SAP Web Dispatcher being monitored

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
totcache Indicates the total number of entries in the cache. Number A high value is desired for this measure.
invalidcache Indicates the number of expired or invalidated entries in the cache. Number If there are too many invalid entries, it indicates that the cache has become stale. If the value of this measure is gradually increasing, then it indicates that the cache is not sized adequately. The appropriate cache needs to be resized using the icm/HTTP/server_cache_/max_entries and icm/HTTP/server_cache_<xx>/size_MB parameters
percInvalid Indicates the percentage of expired or invalidated entries in the cache. Percent This measure is the ratio of the invalidcache to totcache measure.

A low value is desired for this measure.
totSize Indicates the total size of all cache entries in the cache. KB