Chapter 4. Supported configurations
Red Hat OpenShift Container Storage is deployed as a minimal cluster of 3 worker nodes. Spread the nodes across three different availability zones to ensure availability.
4.1. Using dynamically created storage
Red Hat OpenShift Container Storage supports different storage disk sizes with a capacity of 0.5 TiB, 2 TiB and 4 TiB when storage is dynamically created.
4.1.1. Storage class requirements
Red Hat OpenShift Container Storage makes use of the Red Hat OpenShift Container Platform default storage class, and expects a certain default storage class depending on your infrastructure provider.
These classes are configured on Red Hat OpenShift Container Platform nodes automatically, but if your Red Hat OpenShift Container Platform node uses a different storage class as the default, you must change the default storage class back to the appropriate storage class for your infrastructure provider.
-
On Amazon Web Services, the default storage class must be
gp2. -
On VMware vSphere, the default storage class must be
thin.
4.1.2. Sizing and scaling for dynamic storage
The initial cluster of 3 nodes can later be expanded with a recommendation of up to 9 disks in each node. In case of more than 3 worker nodes, the distribution of the disks depends on OpenShift scheduling and available resources.
Expand the cluster in sets of three nodes to ensure that your storage is replicated, and to ensure you can use at least three availability zones.
You can expand the storage capacity only in the increment of the capacity selected at the time of installation.
The following tables shows the supported configurations for Red Hat OpenShift Container Storage.
| Disks | Disks per node | Total capacity | Usable storage capacity |
|---|---|---|---|
| 0.5 TiB | 1 | 1.5 TiB | 0.5 TiB |
| 2 TiB | 1 | 6 TiB | 2 TiB |
| 4 TiB | 1 | 12 TiB | 4 TiB |
| Disk size (D) | Disks per node (M) | Total capacity (D * M * N) | Usable storage capacity (D*M*N/3) |
|---|---|---|---|
| 0.5 TiB | 3 | 13.5 TiB | 4.5 TiB |
| 2 TiB | 6 | 108 TiB | 36 TiB |
| 4 TiB | 9 | 324 TiB | 108 TiB |
Always ensure that you have plenty of storage capacity.
If storage ever fills completely, it is not possible to add capacity or to delete or migrate content away from the storage to free up space. Completely full storage is very difficult to recover.
Capacity alerts are issued when cluster storage capacity reaches 75% (near-full) and 85% (full) of total capacity. Always address capacity warnings promptly, and review your storage regularly to ensure that you do not run out of storage space.
If you do run out of storage space completely, contact Red Hat Customer Support.
As of Red Hat OpenShift Container Storage 4.4, installation is supported only on existing Red Hat OpenShift Container Platform nodes. See Deploying OpenShift Container Storage for more information.
4.2. Using local storage devices
Use of local devices requires the installation of the local storage operator using Operator Hub. See Installing OpenShift Container Storage using local storage devices.
4.2.1. Storage sizing and scaling for local devices
For local storage deployment, any disk size of 4 TiB or lesser can be used, and all disks must be in the same size and type.
The initial cluster of 3 nodes can later be expanded with a recommendation of up to 9 disks in each node. In case of more than 3 worker nodes, the distribution of the disks depend on OpenShift scheduling and available resources.
Always ensure that you have plenty of storage capacity.
If storage ever fills completely, it is not possible to add capacity or to delete or migrate content away from the storage to free up space. Completely full storage is very difficult to recover.
Capacity alerts are issued when cluster storage capacity reaches 75% (near-full) and 85% (full) of total capacity. Always address capacity warnings promptly, and review your storage regularly to ensure that you do not run out of storage space.
If you do run out of storage space completely, contact Red Hat Customer Support.
