Preparing the Search Cluster

Perform the following steps to prepare the search servers for Elasticsearch.

Verify the servers against the Hardware Requirements for Elasticsearch.
Appropriately cable the servers to your network infrastructure so they are reachable from the Swarm nodes.
Install RHEL/CentOS 7 Linux and apply any required updates. Contact DataCore Support for questions about enabling or disabling IPv6.
Best practice

Use RHEL/CentOS Minimal Server (with Compatibility Libraries), which is the standard for Swarm development and testing. RHEL/CentOS Desktop consumes extra resources that Elasticsearch can use, alters the OS configuration to emphasize user interface vs. server performance, and requires additional updating and security maintenance.
Configure the servers with static IP addresses.
Configure DNS, if desired.
Adjust the server firewall rules. See https://firewalld.org.
Adjust the rules to permit the following ports if on CentOS 7 install and run iptables:
- Allow public access on these ports:
```
firewall-cmd --permanent --zone=public --add-port=9200/tcp
firewall-cmd --permanent --zone=public --add-port=9300/tcp
firewall-cmd --reload
```
- Search the Support portal for SwarmNFS 2.x - Access to Elasticsearch (IPTables) for SwarmFS access.

Important

Elasticsearch 7 bundles Java so there is no need to install OpenJDK for it. Use the below command to remove that installed OpenJDK if already installed earlier for Elasticsearch 6.

Remove OpenJDK Package

yum remove java-1.8.0-openjdk