Feature Overview (aka. Goal Summary)  

vSphere 8 now allows 255 volumes per VM (i.e OCP workers) and we use the default value of 59 which is safe for vsphere 7 but vsphere 8 customers want to be able to benefit from the new increased limit.

Goals (aka. expected user outcomes)

Keep maxAllowedBlockVolumesPerNode default to 59 but allow customers to configure the value themselves.

Requirements (aka. Acceptance Criteria):

New API to let customers configure maxAllowedBlockVolumesPerNode in the vsphere CSI driver configuration (MAX_VOLUMES_PER_NODE CSI config), the value should propagated to all nodes. We should make sure that the value is within the supported range before applying it. Also mark the cluster unupgradable if we detect this setting has been applied on a env that contains vsphere 7 hosts.

Anyone reviewing this Feature needs to know which deployment configurations that the Feature will apply to (or not) once it's been completed.  Describe specific needs (or indicate N/A) for each of the following deployment scenarios. For specific configurations that are out-of-scope for a given release, ensure you provide the OCPSTRAT (for the future to be supported configuration) as well.

Use Cases (Optional):

As an OCP admin on top of vsphere 8 i want to increase the maximum number of volumes that can be attached to OCP workers. This allows me to attach more PVCs per workers.

Questions to Answer (Optional):

Confirm that vsphere need to have pvscsiCtrlr256DiskSupportEnabled set to true to increase the limit. ---- yes confirmed !

Confirm VMware has support for pvscsiCtrlr256DiskSupportEnabled option + official doc link

Out of Scope

Autoconfigure based on vsphere version

In order to limit potentials failures, reduce the complexity of that epic and deliver it in time, we are going to limit this feature to homogeneous vsphere 8 environments which only contains ESXi 8 hypervisors. Heterogeneous environment which contain a mix of ESXi 7 & 8 will not be allowed to use this feature. This will be explicitly documented.

Background

The limit was safe in the past but the new vsphere 8 limit requires us to make this option configurable

Customer Considerations

Make sure we document the limit of 255 which is applicable to vsphere 8+ only and we don't support it in mixed ESXi 7&8 environments.

Documentation Considerations

Document how to override MAX_VOLUMES_PER_NODE + current limit (255).
Mention that vsphere 7 is still limited to 59

In order to limit potentials failures, reduce the complexity of that epic and deliver it in time, we are going to limit this feature to homogeneous vsphere 8 environments which only contains ESXi 8 hypervisors. Heterogeneous environment which contain a mix of ESXi 7 & 8 will not be allowed to use this feature. This will be explicitly documented.

Interoperability Considerations

Since vsphere 7 does not support this we will only support it on homogenous vsphere 8 environments.