Editing application server load balancing properties

You can tune Tarantella load balancing by editing application server load balancing properties. The properties are stored in a properties file, which you can edit with a text editor. There are three properties files:

a global properties file, which contains the default settings for the array.
an application server-specific properties file, which allows you to override some of the global settings for a particular application server.
a UNIX application server properties file, which contains the settings the UNIX load balancing service uses when it is first started or re-started.

This topic describes how you edit the properties files and what properties are available. For detailed information on how to use the properties, see Tuning application server load balancing.

Only edit these properties if you are sure you know what you're doing.

The global load balancing properties file

The file tier3lb.properties contains the default load balancing properties for the array. The file is in the install_dir/var/serverconfig/global directory. You should only edit these properties on the primary Tarantella server in the array. The primary will copy the amended files to the secondaries.

In the tier3lb.properties properties file, the properties are prefixed with tarantella.config.tier3lb, for example tarantella.config.tier3lb.weighting.

The table below:

lists the properties you can change,
gives the default value of the property when Tarantella is first installed,
explains what each property is used for, and
indicates whether you can override the property in an application server-specific properties file.

Property	Default value	Purpose	Can be overridden?
`connectretries`	`3`	The number of times the Tarantella server tries to connect to the application server to request CPU/memory updates.	No
`listeningport`	`3579`	The UDP port the Tarantella server uses to listen for data sent by the load balancing service.	No
`longtimeout`	`900`	The pause in seconds between groups of attempts by the Tarantella server to connect to the application server.	No
`maxmissedsamples`	`20`	The number of missed samples used to calculate whether the CPU/memory data for the application server is too unreliable to be used.	No
`probe.listeningport`	`3579`	The TCP port the load balancing service uses to listen for requests from Tarantella servers, for example, when to start sending updates.	Yes
`probe.percentchange`	`10`	The minimum percentage increase or decrease in CPU/memory use that must be reported to the Tarantella server.	Yes
`probe.replyfrequency`	`30`	The interval in seconds at which the load balancing service sends CPU/memory measurements to the Tarantella server. The minimum value for this property is 2.	Yes
`probe.samplerate`	`15`	The interval in seconds between CPU/memory measurements. The minimum value for this property is 1.	Yes
`probe.windowsize`	`3`	The number of CPU/memory measurements used to calculate the CPU/memory average. The minimum value for this property is 1.	Yes
`scaninterval`	`60`	The interval in seconds between scans of the Tarantella server's list of load-balanced application servers.	No
`shorttimeout`	`60`	The interval in seconds between attempts by the Tarantella server to connect to the application server.	No
`sockettimeout`	`5`	The socket timeout in seconds.	No
`updatelimit`	`5`	The limit used to calculate when the load balancing service has stopped sending updates.	No
`weighting`	`100`	The weighting of load measurements relative to the other application servers.	Yes

Note The following properties also appear in the tier3lb.properties properties file, but they must not be changed:

tarantella.config.name=tier3lb
tarantella.config.type=server

The application server load balancing properties file

You can override some of the array default properties by creating a server-specific load balancing properties file. You have to manually create this file in the install_dir/var/serverconfig/global/t3hostdata directory. You should only create a server-specific properties file on the primary Tarantella server in the array. The primary will copy the file to the secondaries.

The properties you can override are shown in the table above.

In the server-specific properties file, the properties are prefixed with tarantella.config.tier3hostdata, for example tarantella.config.tier3hostdata.weighting.

To create a server-specific properties file:

On the primary Tarantella server, change to the install_dir/var/serverconfig/global/t3hostdata directory.
Copy the template.properties file to a file called hostname.properties in the same directory, for example, paris.indigo-insurance.com.properties.
Open the file in a text editor.
Find the line containing the tarantella.config.tier3hostdata.name property.
After the "=", add the ENS name of the application server. The name must be enclosed in quotes and each part of the host name must be escaped using a backslash. For example, to apply the properties to the host o=Indigo Insurance/cn=paris.indigo-insurance.com, type "o\=Indigo Insurance/cn\=paris.indigo-insurance.com".
Uncomment the lines (by deleting the "#") which contain the properties you want to be override. Only uncomment the properties you want to be different from the array defaults.
Change the values of the properties you want to override.
Save the changes and close the file.
Do a warm restart of the primary Tarantella server (tarantella restart --warm).

Note The template.properties file contains comments to help you create a server-specific file.

The UNIX application server properties file

The UNIX application server properties file contains the settings that are used when the load balancing service is first started or whenever the service is restarted, for example if the server is rebooted.

The properties file is installed in the same directory as the Tarantella Enhancement Module on the application server. By default, this is /opt/tta-tem.

You should only make changes to these properties:

if you have been asked to by Tarantella Support; or
if you change the physical or virtual memory of the application server and you have not re-installed the Tarantella Enhancement Module.

If you change these properties, you must manually stop and restart the load balancing service.

In the UNIX server properties file, the properties are prefixed with tarantella.config.tier3loadbalancing, for example tarantella.config.tier3loadbalancing.port.

Related topics
Introducing application server load balancing Configuring application server load balancing Troubleshooting CPU/memory-based application server load balancing Editing application server load balancing properties Setting up a Tarantella Enhancement Module