IP quorum application

The IP quorum application is a Java™ application that runs on a server that is separate from the storage system. There are two types of IP quorum application:

  • A system IP quorum application is only used for single-system tie-break if half of the nodes are unavailable, and optionally for metadata storage
  • A partnership IP quorum application is only used to arbitrate between systems in a policy-based high availability partnership. The IP quorum application can be generated on either system in the partnership. The partnership must be created before generating and deploying the IP quorum application.

The maximum number of IP quorum applications that can be deployed on a single system is five. This enables multiple servers to be used to provide redundancy. Only one instance of the IP quorum application per server, per system, is supported. For example, a server can run two IP quorum instances if each instance is connected to a different nonpartnered storage system. Ensure that bandwidth is available to support multiple IP quorum instances.

Do not deploy the IP quorum application on a server that depends on storage that is presented by the system. This action can result in a situation where the nodes need to detect the IP quorum application to process I/O, but cannot because the IP quorum application cannot access storage.

An Ethernet connectivity issue can prevent an IP quorum application from accessing a node that is still online and an event is raised on the system if this occurs.

Refer to the following support article for the IP quorum application requirements: https://www.ibm.com/support/pages/node/7013877
Warning: For the IP quorum application to be able to connect using TLS 1.3 (SSL Security Levels 6 and 7), the version of Java running the application must also support TLS 1.3.

Configuring IP Quorum on the storage system

You can configure IP quorum on the storage system by using the GUI or CLI:

Using the management GUI
In the management GUI, the Policy-based replication setup procedure includes generating the IP quorum application.
Using the CLI
On the CLI, enter the command: mkquorumapp -partnersystem <remote system ID or name>

Deploying the IP Quorum Application on the server

Follow these steps to deploy the IP quorum application on the server:
  1. Create a separate directory that is dedicated to the IP quorum application.
  2. Transfer the IP quorum application from the storage system to the dedicated directory.
  3. Use the ping command on the server to verify that it can establish a connection with the service IP address of each node in both systems.
  4. Enter the command java -jar ip_quorum.jar to initialize the IP quorum application.
    Note: The IP quorum application needs to be running always.
The options available when running the IP quorum application can be listed with -help:

1. $ java -jar ip_quorum.jar -help
2. -name (optional) to help identify the IP quorum app instance in the GUI/lsquorum.  Can only contain 1-20 characters that are A-Z, a-z or 0-9.
3. -debug (optional) run the app in debug mode to display verbose messages on stdout and in the log file.
4. -emit (optional) display T3 metadata header information
5. -location (optional) default = ip_quorum.log.16845080043810. Specify the full, or relative path to store your log files. Allowed characters: [a-z A-Z 0-9 .-_/] 
6. -rotation (optional) default = 5. Specify the maximum number of log files. Allowed values: [1-10]
7. -size (optional) default = 5120. Specify the log file size in kb. Allowed values: [1024-10240]
8. -version / -v (optional) display the vrmf of the system when the app was generated, timestamp and generation id.

Reviewing and monitoring the IP Quorum Application

You can monitor and review the IP quorum application from each system by using the management GUI or CLI:

Using the management GUI
In the management GUI, select Settings > System > IP Quorum.
Using the CLI
Enter the lsquorum command.
The type of quorum application is shown in the application_type field.