This article explains how to configure two Domain Servers as a highly available (HA) pair, and how to enable the Grid feature so that two CEP Servers can operate together for redundancy.

Prerequisites

• Two Domain Server VMs are provisioned, each with the meshIQ Platform Domain component installed, and each can reach the other over the network.

Configure Domain High Availability

Configure each Domain VM with its instance ID and the hostname or IP address of its peer. This allows the two Domain Servers to coordinate HA failover.

1. Replace the Domain HA scripts

   On both Domain VMs, replace the existing start.sh, stop.sh, show.sh, and MONITORING.DOMAIN.sh scripts with the versions provided for this configuration. This can be obtained from your consultant, or these scripts might be there already.

   These updated scripts contain the logic needed to start, stop, check the status of, and monitor a Domain instance that is part of an HA pair.

2. Set the Domain instance environment variables

   On each Domain VM, open apin_env.sh and add the two environment variables. The values differ on each VM, as shown below:

   # On Domain VM 1
   export DOMAIN_INSTANCE=1
   export DOMAIN_HOST_NAME=<hostname_or_ip_of_domain_vm_2>

    

   # On Domain VM 2
   export DOMAIN_INSTANCE=2
   export DOMAIN_HOST_NAME=<hostname_or_ip_of_domain_vm_1>

   Each Domain VM must point to its peer, not to itself. DOMAIN_HOST_NAME on Domain VM 1 is the address of Domain VM 2, and vice versa.

Enable the CEP Grid

Link CEP1 and CEP2 into a single Grid and connect that Grid to the Domain HA pair configured earlier.

Complete these steps after Domain configuration is complete.

1. Enable the grid properties on each CEP instance

   On each CEP VM, open node.properties, located in /opt/meshiq/platform/localhost. The grid properties already exist in this file, only need to set their values as shown below.

   For the CEP1 instance

   property server.grid = APGrid
   property server.grid_enabled = true
   property server.grid.pri = 0

   For the CEP2 Instance

   property server.grid = APGrid
   property server.grid_enabled = true
   property server.grid.pri = 1

   server.grid must be set to the same value (In this case, it APGrid & can be any value) on both CEP instances so that they recognize each other as members of the same grid.

    

2. Copy the existing CEP registry.xml file to both Domain VMs

   Locate the existing registry.xml file in /opt/meshiq/platform/localhost. Copy this file to both Domain VMs, placing it at the following path on each:

   /opt/meshiq/platform/naming/grid/APGrid

   If the naming, grid, or APGrid (or the grid name defined in CEPs node.properties file) directories do not already exist on a Domain VM, create them manually under /opt/meshiq/platform/naming before copying the file.

    

3. Configure the CEP Server to Use Both Domain VMs

   On the CEP VM, open global.properties, and set the following two properties to the hostnames of Domain VM 1 and Domain VM 2 respectively:

   Property	Value
   domain.server.url	Domain VM1 hostname
   domain.server.failover.url	Domain VM2 hostname

   With this in place, the CEP Server connects to Domain VM 1 by default and automatically fails over to Domain VM 2 if Domain VM 1 becomes unreachable.