Configuring the quorum mechanism

Configure the quorum mechanism for each catalog server. You must enable the quorum mechanism on all of the catalog servers in the catalog service domain. Changing the quorum configuration requires a restart.

Before you begin

The configuration must support the following requirements:

IP configuration: Any addressable element on the network must be able to connect to any other addressable element on the network unimpeded. All the firewalls in the configuration must allow all traffic to flow between the IP addresses and ports that are being used to host catalog servers and container servers.

About this task

For more information about the quorum mechanism, see Catalog server quorums.

Changing the quorum configuration requires that you restart the catalog server. You can choose one of the following processes to enable the quorum configuration on the catalog servers in your catalog service domain:

Stop the entire catalog service domain, change the setting, and restart the catalog service domain.
Stop and start one catalog service at a time. With this process, some catalog servers have quorum enabled while other catalog servers do not. If container server outages occur during this process, container server lifecycle events occur only if the primary catalog server does not have quorum yet, or when you override quorum.

Procedure

Enable quorum on the catalog servers.

In WebSphere® Application Server, you must configure quorum with the server properties file. In a stand-alone environment you can either use the properties method or enable quorum when you start the server:

Set the enableQuorum=true property in the server properties file.
You can use this configuration in a WebSphere Application Server or stand-alone environment. See the following example objectGridServer.properties file:
```
catalogClusterEndPoints=cat0:cat0.domain.com:6600:6601,
cat1:cat1.domain.com:6600:6601
catalogServiceEndPoints= cat0.domain.com:2809, cat1.domain.com:2809
enableQuorum=true
```
For more information about configuring the properties file, see Server properties file.
Pass the -quorum enabled flag on thestartOgServeror startXsServer command.
You can use this configuration method when you start stand-alone servers only.
```
# bin/startOgServer cat0 –serverProps objectGridServer.properties -quorum true
```
```
# bin/startXsServer cat0 –serverProps objectGridServer.properties -quorum true
```
For more information about the startOgServeror startXsServer command, see Starting and stopping stand-alone servers.

In order to enable majority quorum, you must enable quorum in the server properties file, and then enable majority quorum on the catalog servers.
1. Set the enableQuorum=true property in the server properties file.
  You can use this configuration in a WebSphere Application Server or stand-alone environment. See the following example objectGridServer.properties file:
```
catalogClusterEndPoints=cat0:cat0.domain.com:6600:6601,
cat1:cat1.domain.com:6600:6601
catalogServiceEndPoints= cat0.domain.com:2809, cat1.domain.com:2809
enableQuorum=true
```
  For more information about configuring the properties file, see Server properties file.
2. Set the -Dcom.ibm.websphere.objectgrid.server.catalog.majority.quorum=true JVM property when you start a catalog server.
```
./startXsServer.sh cs1 -catalogServiceEndpoiints <some_hostnames_and_port_numbers> -jvmArgs
    -Dcom.ibm.websphere.objectgrid.server.catalog.majority.quorum=true
```

Results

By enabling the quorum mechanism on the catalog servers within a catalog service domain, all the catalog servers must be available for data grid placement operations to occur. If a short network brownout occurs, placement operations are temporarily stopped until all the catalog servers in the quorum are available. To verify the quorum settings, run the xscmd command showQuorumStatus.

You can add catalog servers to the quorum by repeating these steps.

What to do next

For more information about dealing with outages and overriding the quorum mechanism, see Managing data center failures when quorum is enabled.