Citrix Server Load Test

The Load evaluator is a thread in the IMA Service on a Virtual Apps Server that calculates the load index for that server. The load index is an integer value from 0 to 10,000 that represents how busy the Virtual Apps server is.

Citrix administrators need to continuously track changes to the load index of a Citrix server, so that they can quickly isolate current/potential overload conditions on a server. Load index monitoring will also enable administrators understand the dynamics of load on the server, so that they can, if need be, reconfigure the load rules associated with the load evaluator according to the changes observed in load trends. For such load-level insights, administrators can use the Citrix Server Load test. If a load evaluator is configured for a monitored Virtual Apps server, then this test will reveal the load index value of that server and will instantly alert administrators if the server is fully loaded. This way, the test warns administrators of a probable overload condition on the server.

Target of the test : Any Citrix server

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for the Citrix server monitored

Configurable parameters for the test
TEST PERIOD – How often should the test be executedor Host – The host for which the test is to be configured Port – Refers to the port used by the Citrix server

Measurements made by the test

Measurement

Description

Measurement Unit

Interpretation

Server load:

Indicates the current load index value of the server.

Number

The current load index is a result of the calculations and sum of the values of all the rules in each and every load evaluator which applies to the server.

Each load evaluator contains one or more rules. Each rule defines an operational range for the server or published application to which its evaluator is assigned. Some of these rules are as follows:

Rule	Description
Application User Load	Limits the number of users allowed to connect to a selected published application. The default value to report full load is 100.
Context Switches	Defines a range of context switches per second for a selected server. The default value to report full load is 16000.
CPU Utilization	Defines a range of processor utilization, as a percentage, for a selected server. The default value to report full load is 90 percent.
Disk Data I/O	Defines a range of data throughput, in kilobytes per second, for a selected server. The default full load value is 32767 kilobytes per second.
Disk Operations	Defines a range of disk operation, in read/write cycles per second, for a selected server. The default full load value is 100 operations per second.
Memory Usage	Defines a range of memory usage by a server. The default full load value is 90.
Page Fault	Defines a range of page faults per second for a selected server. A page fault occurs when the operating system tries to access data that was moved from physical memory to disk. The default full load value is 2000.
Page Swaps	Defines a range of page swaps per second for a selected server. A page swap occurs when the operating system moves data between physical memory and the swap file. The default full load value is 100.
Server User Load	Limits the number of users allowed to connect to a selected server. The default full load value is 100 and represents the maximum number of users the system can support on a server.

The base algorithm for establishing actual load is:

Highest_Load + (Average_Other_Loads * .1)

The resultant value is reported as the value of this measure.

If the value of this measure is in the range of 0 to 9998, it implies that the server load is normal. On the other hand, if the measure value touches or exceeds 10000, it implies that server load is at 100%. In this case, Virtual Apps automatically removes the load-managed server from the internal list of available servers. The next request for an ICA connection to a published application is routed to the next available load-managed server in the list.

One important factor to understand is once any single rule reaches its maximum value, the load value for that server becomes 10,000, effectively removing the individual server from contention for new sessions.

Is load evaluator configured ?

Indicates whether or not any load evaluator has been configured for the server.

If the Server load measure reports the value 99999, this measure will return the value No, indicating that no load evaluator has been configured for the server. On the other hand, if the Server load measure reports a value between 0 and 9998 or the value 10000, then, this measure will report the value Yes; this indicates that a load evaluator has been configured for the server.

The numeric values that correspond to these Yes and No measure values are listed below:

Measure Value	Numeric Value
Yes	1
No	0

Note:

By default, this measure reports the Measure Values listed in the table above to indicate whether/not the server has been configured with a load evaluator. In the graph of this measure however, the same is represented using the corresponding numeric equivalents only.

Is server fully loaded?

Indicates whether/not the server is fully loaded.

If the Server load measure reports the value 10000, this measure will return the value Yes, indicating that the server is fully loaded. One important factor to understand is once any single rule associated with the load evaluator of the server reaches its maximum value, the load value for that server becomes 10000.

On the other hand, if the Server load measure reports a value between 0 and 9998, then, this measure will report the value No; this indicates that the server is not fully loaded.

The numeric values that correspond to these Yes and No measure values are listed below:

Measure Value	Numeric Value
Yes	1
No	0

Note:

By default, this measure reports the Measure Values listed in the table above to indicate whether/not the server is fully loaded. In the graph of this measure however, the same is represented using the corresponding numeric equivalents only.

Is there a license/edition mismatch?

Indicates if an incorrect server edition is being used or a license mismatch has been detected.

If the Server load measure reports the value 20000, this measure will return the value Yes, indicating that the AppCenter console contains an incorrect server edition or a license mismatch.

On the other hand, if the Server load measure reports a value between 0 and 9998, the value 10000, or the value 99999, then this measure will report the value No; this indicates that no such mismatch has been detected.

The numeric values that correspond to these Yes and No measure values are listed below:

Measure Value	Numeric Value
Yes	1
No	0

Note:

By default, this measure reports the Measure Values listed in the table above to indicate if the server edition is incorrect or the license does not match. In the graph of this measure however, the same is represented using the corresponding numeric equivalents only.