Sybase Cache Test

This test reports the statistics pertaining to the default data cache and for all the named caches configured in a Sybase database server.

Target of the test : A Sybase ASE (Below v15) server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the default cache and every named cache 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 server.

Port

The port number at which the Sybase server listens to.

User

A Sybase user who has the “sa_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 suite 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

Cache utilization

The number of searches using this cache as a percentage of searches across all caches.

 

Percent

Compare this value for each cache to determine if there are caches that are over or under-utilized. If you decide that a cache is not well utilized, you can

  • Change the cache bindings to balance utilization
  • Resize the cache to correspond more appropriately to its utilization

Cache hit ratio

The percentage of times that a required page was found in the data cache.

Percent

A low value indicates that the cache may be too small for the current application load.

Spinlock contention

The number of times an engine encountered spinlock contention on the cache, and had to wait, as a percentage of the total spinlock requests for that cache.

Percent

If spinlock contention is more than 10%, consider using named caches or adding cache partitions.

Buffers grabbed

The average number of times that Adaptive Server fetched a buffer from the LRU end of the cache, replacing a database page.

Buffers/Sec

The detailed diagnosis of this measure, if enabled, reports the buffers grabbed for each configured memory pool. If this value is high in some pools and low in other pools, you might want to move space from the less active pool to the more active pool, especially if it can improve the cache-hit ratio.

Dirty buffers grabbed

The average number of times that fetching a buffer found a dirty page at the LRU end of the cache and had to wait while the buffer was written to disk.

Buffers/Sec

A nonzero value indicates that the wash area of the pool is too small for the throughput in the pool. The detailed diagnosis of this measure, if enabled, reports the dirty buffers grabbed for each configured memory pool.

Large I/Os denied

The number of large I/O requests denied as a percentage of the total number of requests made

Percent

Large I/O requests are denied due to the following reasons:

  • If any page in a buffer already resides in another pool.
  • When there are no buffers available in the requested pool.
  • On the first extent of an allocation unit, since it contains the allocation page, which is always read into the 2K pool.

If a high percentage of large I/Os were denied, it indicates that the use of the large pools might not be as effective as it could be.

Large I/O effectiveness

The total number of pages that were used after being brought into cache by large I/O

Percent

A low value indicates that only few of the pages brought into cache are being accessed by queries.