Sybase Data Cache Test

Data caches in ASE hold the data, index, and log pages currently in use, as well as recently used pages in memory. These caches are critical in providing high levels of system performance as they effectively avoid expensive disk I/O.  Inadequately sized data caches can increase the incidence of physical disk accesses, thereby affecting the performance of the Sybase server. Periodic monitoring of the usage of the data cache is essential to determine whether the cache needs to be resized or not.

This test auto-discovers the data caches on the Sybase server, and tracks the usage of each cache. Frequently used objects and objects that occupy the memory are listed in detailed diagnosis. For this test to work, make sure that the enable monitoring parameter is enabled.

Target of the test : A Sybase ASE server on which the MDA tables have been installed

Agent deploying the test : An internal agent

Outputs of the test : One set of results for every database being monitored

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	Refers to the IP address of the Sybase ASE server.
Port	The port number at which the Sybase server listens to.
User	To enable this test to connect to the Sybase server and collect the required metrics, it is enough if you configure the test with the name of a Sybase user who has the “mon_role”. However, for best results, it is recommended that you configure all Sybase tests with the credentials of a Sybase user who has the “mon_role”, “sa_role’, and “sybase_ts_role”.
Password	The password corresponding to the above user
Confirm Password	Confirm the password by retyping it here.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled: The eG manager license should allow the detailed diagnosis capability Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Data cache hit ratio	The hit ratio of each data cache in the Sybase server.	Pct	If the value of this measure is low, it indicates that too many physical reads are occurring on the Sybase server. If the problem persists, it could result in a serious contention for disk resources, which in turn, can cause the performance of the Sybase server to significantly deteriorate. You might want to consider resizing the data cache to avoid this adversity. The detailed diagnosis for this measure provides a list of objects that occupy the memory in cache, so that we can easily identify the objects that are consuming too much memory, and accordingly initiate corrective actions.
Number of objects	The number of objects in each cache.	Number	Use the detailed diagnosis of this measure to view the list of objects in cache; this reveals the objects that are frequently accessed by users.

The detailed diagnosis of the Data cache hit ratio measure reveals the objects that are in cache and the memory space occupied by each object. This way, you can quickly identify which objects are occupying the maximum space in the cache, check whether these objects are been used frequently, and if not, remove the objects from the cache, so as to free space.

Figure 1 : The detailed diagnosis of the Data cache hit ratio