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Chapter 8 Performance Tuning and Load Balancing Mechanisms in Communications ExpressThis chapter describes the information you need to consider for improving the performance of Communications Express. LDAP Failover Mechanism in Communications ExpressThis section describes how to set up and configure LDAP pools and set LDAP connections to improve the efficiency of Communications Express. Some components of Communications Express require connections to the LDAP server to retrieve and manage information. The amount of time required to establish a connection and retrieve information from the LDAP server can be huge if a large number of users are logged in. You can reduce the turnaround time to establish the connection and retrieve information if a pool of LDAP connections are already created which Communications Express can use. In a typical production environment of Communications Express, an LDAP load balancing and failover mechanism is adopted. Here, one LDAP server (known as the master) is responsible for retrieving information and another set of servers (known as the failover servers) are used in case of a catastrophe (where the master server fails). This way, a single point of failure is avoided. Communications Express contains an LDAP failover Manager module that is responsible to retrieve connections from the master or slave servers. Each load balancing server maintains a pool of available free connections. Whenever a Communications Express component requires a connection to the LDAP server, the LDAP failover manager provides the component with a connection from the pool of LDAP connections.
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<session-config>
<session-timeout>10</session-timeout>
</session-config>
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Tuning LDAP Related Configuration Parameters
This section describes the tuning you can perform on Directory Server to enhance performance.
Setting the nsSizeLimit and nsLookthroughLimit Parameters for Users and Address Book
It is important that the nsSizeLimit and nsLookthroughLimit parameters in User or Group LDAP directory and Address Book server configuration is large enough for searches to be completed properly.
To determine if these parameters are set to appropriate values, type the following command:
ldapsearch -b /base/ (&(icscalendarowned=*/user/*)(objectclass=icsCalendarUser))
where
/base/ is the LDAP base DN of the directory server where the user and resource data for Calendar Server is located.
/user/ is the value that an end user can enter in the Calendar Search dialog under the Subscribe option in Communications Express.
The LDAP server returns an error, if the nsSizeLimit or the nsLookthroughLimit parameter is not large enough.
Follow these guidelines to reset nsSizeLimit or the nsLookthroughLimit parameters:
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Ensure that the value for nsSizeLimit parameter is large enough to return all the desired results, otherwise, data can get truncated, and no results will be displayed.
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Ensure that the value for nsLookthroughLimit parameter is large enough to complete a search of all the users and resources in the LDAP directory. If possible set nsLookthroughLimit to -1. By doing this, no search limit is set for nsLookthroughLimit.
Note –
It is recommended that the User or Group and Address Book entries in LDAP are setup separately.
Tuning Web Server
To enhance the Web Server's performance, perform the steps described in this section.
Setting The Value of acceptorthreads
In server.xml, change the value of the attribute acceptorthreads present in <vs\> (virtual server) element to the number of CPUs on the machine hosting Web Server.
For example:
<VS id="https-siroe.com"
connections="ls1"
mime="mime1"aclids="acl1"
urlhosts="<webserver hostname"
acceptorthreads="<noofcpus\>" \>
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Setting JVM Options
Add or set the following JVM options in the server.xml file of Web Server.
The following parameters determine the heap size of JVM
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<JVMOPTIONS>-Xms/JVMOPTIONS> (approximate value according to the memory available)
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<JVMOPTIONS>-Xmx /JVMOPTIONS>(approximate value according to the memory available)
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<JVMOPTIONS>—XX: NewSize = <1/3rd of the heap allocated></JVMOPTIONS>
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<JVMOPTIONS>-XXMaxNewSize =<1/3rd of the heap allocated></JVMOPTIONS>
The first option indicates Maximum heap size and the second option indicates Minimum heap size
It is recommended to have the same values for both the options.
Add the following JVM option
JVMOPTIONS -server /JVMOPTIONS
Set the following parameters for garbage Collection
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JVMOPTIONS-XX:+UseParNewGC/ JVMOPTIONS
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JVMOPTIONS-XX:ParallelGCThreads= number-of-CPUs/JVMOPTIONS
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JVMOPTIONS-XX:+UseConcMarkSweepGC/ JVMOPTIONS
Tuning Calendar Server
This section describes how load balancing across multiple CPU on Calendar Server can enhance performance.
Using Load Balancing Across Multiple CPU
If a server has multiple CPUs, by default Calendar Server distributes the HTTP Service such as cshttpd processes and Distributed Database Service such as csdwpd processes across CPUs.
The service.http.numprocesses and service.dwp.numprocesses parameters in the ics.conf file determine the actual number of processes that run for each service. By default, these parameters are set to the number of CPUs for the server during installation, but you can reset these values. For example, if a server has eight CPUs, but you want a cshttpd and csdwpd process to run in only 4 CPUs, set the parameters as:
service.http.numprocesses="4"
service.dwp.numprocesses="4"
To Disable Load Balancing
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Add the service.loadbalancing parameter to the ics.conf file
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Set service.loadbalancing to “no.”
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Restart Calendar Server for the change to take effect.
For information on load balancing refer to Appendix C, Calendar Server Configuration Worksheet, in Sun Java System Calendar Server 6.3 Administration Guide in Sun Java System Calendar Server 6.3 Administration Guide