Memory and CPU resource allocations

A minimum amount of resources must be available for each VM if the hypervisor is configured to enforce minimum reservations.

In SMU software version 12.5.4038.04 or later for VMware, and version 12.7.411.xx or later for Hyper-V, the virtual SMU supports up to 10 managed servers or clusters.

The virtual SMU should be allocated 1 GiB RAM and 1 CPU core per managed server or cluster, regardless of the number of nodes in a cluster. For example, to manage four HNAS clusters, the virtual SMU should be allocated 4 GiB RAM and 4 CPU cores. The virtual SMU’s minimum requirement is 4 GiB RAM for CentOS Stream 8, and 2 CPU cores, which is the default when it is deployed.

Note: If a server or cluster has more than 128 filesystems, the minimum requirements are 4 GiB RAM and a minimum of 2 CPU cores allocated to the virtual SMU with a maximum of two clusters per virtual SMU.

Sufficient memory and CPU resources allocated to the virtual SMU ensure that:

The SMU's quorum device has enough priority on an oversubscribed host to maintain real-time communication with an HNAS cluster.
Sufficient resources are available for background monitoring, which the SMU performs for each managed server cluster.

Important: The quorum device must respond to cluster heartbeats (over UDP) within five seconds to prevent the possibility of dependent and degraded HNAS clusters rebooting. Make sure that the SMU VM always has sufficient resources so that the quorum device is not paused or unresponsive for more than five seconds.

Resource reservations are less important when the SMU is not used as a quorum device.

Note: The NAS module in VSP models uses a different mechanism to control High Availability, so it does not use the SMU's quorum device.