Multiple racks
The multiple rack topology offers these variants: high-availability multi-rack, 3 zone high-availability multi-rack, and expansion rack.
Expansion racks
With expansion racks, you begin with a single rack during installation. Later, add more racks to meet your evolving memory, CPU, and storage needs.
The expansion racks do not need a spine switch for connectivity for the Fusion Data Foundation storage type. For Global Data Platform storage type, spine switches are needed for expansion rack connectivity.
High-availability multi-rack and 3 zone HA rack
- High-availability multi-rack
- In high-availability multi-rack, at installation time, you can connect three IBM Fusion HCI System racks to create a single large OpenShift® Container Platform cluster. The
control nodes are distributed across multiple racks for fault tolerance. Order three similar racks
from IBM factory with a minimum of six storage nodes per rack.
In the IBM Fusion HCI System with Fusion Data Foundation storage, the uplink carries the OpenShift VLAN as well as the management or provisioning VLAN 4091 on the uplink, and there are no spine switches. For network prerequisites, see Network for multi-rack HA.
- 3-Zone HA
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IBM Fusion HCI System supports 3 zone HA where the racks are distributed across distinct locations within a region that are designed to be isolated from failures occurring in other zones. For 3 zone HA, each rack must be connected to the customer switches in such a way that they are in the same broadcast domain.
For both high-availability multi-rack and 3-Zone HA, Fusion Data Foundation is the only supported storage type. The Fusion Data Foundation storage spreads its resources in these three racks so that you do not lose data when a rack goes down either because of maintenance or power failure. The multiple side-by-side (adjacent) appliances act as a single unit and hosts a single Fusion Data Foundation storage and OpenShift Container Platform cluster. To achieve high availability, 1 control node (Rack Unit 2) is available in each of these three racks so even when one rack goes down, the cluster stays available. The components in each of the three racks are the same as a single rack.
The service node can be made available in any one of the racks. The rack to which the service node is connected is designated and used as the base rack.