Basic guidance
The following table provides basic cluster infrastructure guidance. For detailed configuration information, see Cluster Hardware Design. Administrators can build a container cluster to be deployed quickly and reliably when each node is within the validated design guidelines.
Table 1. Hardware infrastructure for OpenShift Container Platform 4.6 cluster deployment
CSAH node |
Dell EMC PowerEdge R640 server |
1 |
Creates a bootstrap VM. CSAH runs a single instance of HAProxy. For enterprise high availability (HA) deployment of OpenShift Container Platform 4.6, Dell Technologies recommends using a commercially supported L4 load-balancer or proxy service or system. Options include commercial HAProxy, Nginx, and F5. |
Controller nodes |
Dell EMC PowerEdge R640 server |
3 |
Deployed using the bootstrap node. |
Compute nodes |
Dell EMC PowerEdge R640 or R740xd server |
Minimum 2,* maximum 30 per rack |
No compute nodes are required for a three-node cluster. A standard deployment requires a minimum of two compute nodes (and three controller nodes). To expand a three-node cluster, you must add two compute nodes at the same time. After the cluster is operational, you can add more compute nodes to the cluster through the Cluster Management Service. |
Data switches |
Either of the following switches:
- Dell EMC PowerSwitch S5248-ON
- Dell EMC PowerSwitch S5232-ON
|
2 per rack |
Autoconfigured at installation time. Note:
- HA network configuration requires two data path switches per rack.
- Multirack clusters require network topology planning. Leaf-spine network switch configuration may be necessary.
|
iDRAC network |
Dell EMC PowerSwitch S3048-ON |
1 per rack |
Used for OOB management. |
Rack |
Selected according to site standards |
1–3 racks |
For multirack configurations, consult your Dell Technologies or Red Hat representative regarding custom engineering design. |
*A three-node cluster does not require any compute nodes. To expand a three-node cluster with additional compute machines, you must first expand the cluster to a five-node cluster using two additional compute nodes.
Installing OpenShift Container Platform requires, at a minimum, the following nodes:
- One CSAH node, which is used to run the bootstrap VM. The CSAH node is used later to manage the cluster while the cluster is in production use.
- Three nodes running both the control plane and data plane, enabling customers to develop OpenShift 4.6 POCs using only four nodes. The cluster can be expanded with additional compute nodes as needed. However, an initial expansion beyond three nodes requires two compute nodes. A four-node cluster (three controllers, one compute) is not supported. The minimum viable solution options are a three-node cluster (three control-compute nodes) or a five-node cluster (three controller nodes, two compute nodes) plus the CSAH node for cluster administration with either option.
HA of the key services that make up the OpenShift Container Platform cluster is necessary to ensure run-time integrity. Redundancy of physical nodes for each cluster node type is an important aspect of HA for the bare-metal cluster.
In this design guide, HA includes the provisioning of at least two network interface controllers (NICs) and two network switches that are configured to provide redundant pathing. The redundant pathing provides for network continuity if a NIC or a network switch fails.
OpenShift Container Platform 4.6 must use Red Hat Enterprise Linux CoreOS (RHCOS) for the control-plane nodes and can use either RHCOS or Red Hat Enterprise Linux 7.6 for compute nodes. Using Red Hat Enterprise Linux 7 on the compute nodes is now deprecated, and the ability to use Red Hat Enterprise Linux 7 compute nodes in OpenShift will be removed in a future release of OpenShift. The bootstrap and control-plane nodes must use RHCOS as their operating system. Each of these nodes must be immutable.
The following table shows the minimum resource requirements:
Table 2. Minimum resource requirements for OpenShift Container Platform 4.6 nodes
CSAH |
Red Hat Enterprise Linux 7.6+ |
4 |
32 GB |
200 GB |
Bootstrap |
RHCOS 4.6 |
4 |
16 GB |
120 GB |
Controller |
RHCOS 4.6 |
4 |
16 GB |
120 GB |
Compute |
RHCOS 4.6 or Red Hat Enterprise Linux 7.6 (deprecated) |
2 |
8 GB |
120 GB |
The RHCOS nodes must fetch ignition files from the Machine Config server. This operation uses an initramfs-based-node startup for the initial network configuration. The startup requires a DHCP server to provide a network connection giving access to the ignition files for that node. Subsequent operations can use static IP addresses.
