Integrated Cache - CCGC Test

The integrated cache provides in-memory storage on the Citrix Cloud Gateway Connector and serves Web content to users without requiring a round trip to an origin server. The cache monitors HTTP and SQL requests that flow through the target server and compares the requests with stored policies. Depending on the outcome, the integrated cache feature either searches the cache for the response or forwards the request to the origin server.  

For best performance, majority of requests for web content should be serviced by the cache, without disturbing the origin server. If the cache is not sized right however, this might not be possible! To quickly detect irregularities in cache usage and sizing, administrators should know how much memory is used up by objects in cache, how much cache memory is free, and whether/not the cache is able to service requests efficiently with the memory available to it. This is exactly what the Integrated Cache - CCGC test reveals!

This test monitors the requests to the cache, checks how well the cache processes the requests, and reveals whether cache misses are more than cache hits or vice versa. In the event that many requests are not serviced by the cache (i.e., if cache misses are more), administrators can use the memory usage statistics reported by this test to figure out if the cache is sized commensurate to its load.

Target of the test : A Citrix Cloud Gateway Connector

Agent deploying the test : A remote agent

Outputs of the test : One set of results for the Citrix Cloud Gateway Connector to be monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The host for which the test is to be configured.

Port

The port at which the connector listens. By default, this is 8443.

Username and Password

To monitor a Citrix Cloud Gateway Connector, the eG agent should be configured with the credentials of a user with read-only privileges to the target connector. Specify the credentials of such a user in the Username and Password text boxes.

Confirm Password

Confirm the Password by retyping it here.

SSL

By default, the SSL flag is set to No indicating that the eG agent will communicate with the connector via HTTP by default. If the target connector is SSL-enabled, then set this flag to Yes to enable the eG agent to communicate with target connector via HTTPS.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Hits

Indicates the number of requests serviced by the cache during the last measurement period.

Number

Ideally, the value of this measure should be high.

Hit rate

Indicates the rate at which the requests were serviced by the cache during the last measurement period.

Hits/sec

 

Hit ratio

Indicates the percentage of requests that have been serviced by the cache.

Percent

Ideally, the value of this measure should be 80% and above. A value lesser than 80% indicates that the cache is unable to service many requests, maybe because the objects requested are not in cache. This could be due to poor cache size. 

Misses

Indicates the number of requests serviced by origin server during the last measurement period.

Number

Ideally, the value of this measure should be 0 or much lower than the value of the Hits measure. A very high value is a cause for concern as it indicates that the cache is poorly utilized.

Miss rate

Indicates the number of requests serviced by origin server per second during the last measurement period.

Misses/sec

 

Origin bandwidth saved

Indicates the percentage of origin bandwidth saved, expressed as the ratio of the number of bytes served from the integrated cache divided by all bytes served.

Percent

The integrated cache saves bandwidth by servicing requests that would otherwise have fetched data from the origin server and consumed considerable bandwidth resources in the process.

This is why, the value of this measure should be high, ideally.

A very low value indicates excessive bandwidth consumption and abysmal bandwidth saving owing to the inability of the cache to service majority of the requests. 

Maximum memory

Indicates the largest amount of memory the target connector can dedicate to caching.

KB

Typically, up to 50% of memory available to the target connector can be allocated for caching. If the global memory limit of the cache is set to 0, it indicates that the integrated cache feature is disabled.

Maximum memory active

Indicates the maximum amount of memory (active value) that will be set after the memory is actually allocated to the cache.

KB

Once the global memory limit is set, you can reset it to any other positive value later. However, this change will not alter the existing memory allocation to the Integrated cache immediately. For instance, you can change the global memory limit from 4000 KB to 6000 KB. But, if you query the memory limit soon after, you will find that while  the Maximum memory measure reports the new memory limit of 6000 KB, the actual memory usage limit in effect currently continues to be 4000 KB and is by Maximum memory active measure. To ensure that the change to the global memory limit is effected, save the new configuration and restart the appliance. Once this is done, then before the Maximum memory and Maximum memory active measures will report the same value.

Memory utilized

Indicates the amount of memory the cache is currently using.

KB

If the value of this measure is very close to the Maximum memory active measure, it indicates that the cache is running out of memory and will not be able to hold any more requested objects.  This will drastically reduce cache hits and increase cache misses. Also, accesses to the origin server will increase, thereby adversely impacting bandwidth usage.

Under such circumstances, you may want to consider resizing the cache by allocating more memory to it.