prereq-summary-multi-master.txt

https://docs.openshift.com/container-platform/latest/install_config/install/planning.html

Summary: 9 VMs recommended for multi master install.  
* Infrastructure (physical or virtual machines, assuming virtual):
* Master Nodes (3 VMs required)
  * 32GB RAM 
  * 4 vCPUs 
  * 50GB Disk (for OS) **(put all of the space in '/' partition.  Do not bother splitting up /var, /usr, /home, etc...)**
  * RHEL7.6 upgraded to latest patchset
* Infrastructure Nodes (3 VMs required)
  * 32GB RAM 
  * 4 vCPUs 
  * 50GB Disk (for OS)
  * 200GB Disk (for OCS, raw/unformatted)  
  * RHEL7.6 upgraded to latest patchset
* Application Nodes (3 VMs recommended) 
  * 32GB RAM 
  * 4 vCPUs 
  * 50GB Disk (for OS)
  * RHEL7.6 upgraded to latest patchset
* Load Balancer (required)
  * if load balancer is not available, an additional RHEL VM can be provsioned for this purpose.  
  * 4GB RAM
  * 1 vCPU
  
* Internet connectivity is recommended
  * HTTPS Whitelist these trusted hosts in proxies and/or firewalls (if needed)
	For content (RPM packages):
	- subscription.rhn.redhat.com
	- cdn.redhat.com
	For docker registry:
	- registry.access.redhat.com
* DNS Requirements 
  * Choose a domain name for Openshift – Example: ocp.example.com
* Create a wildcard entry in parent DNS zone that points to infra structure VMs (round robin)
* Ex:  A record '*.ocp' IN zone 'example.com' (resolves to all three infra nodes)
**This DNS record is absolutely required and is often the most time consuming task to get done (internal approvals are likely required)**

Activate the Openshift subscriptions provided by Red Hat. If using a Satellite Server, synchronize the relevant channels.
   * rhel-7-server-rpms
   * rhel-7-server-extras-rpms
   * rhel-7-server-ose-3.11-rpms
   * rh-gluster-3-client-for-rhel-7-server-rpms
   * rhel-7-server-ansible-2.6-rpms

Additional Considerations:
   1. RHEL7.6 vanilla is recommended (unmodified ISO as it comes from RH)
    - The “Minimum” installation is recommended
   2. SELinux must be in “Enforcing” (default in vanilla image)
    - Test with 'getenforce'
   3. NetworkManager must be enabled (default in vanilla image)
    - Test with 'nmcli dev status'
   4. iptables must be enabled (default in vanilla image)
    - Test with 'systemctl status iptables'