In the vSphere Web Client, an alarm is triggered when vCenter Server detects that a workload from a host might be affecting performance.
The alarm Pre-4.1 host connected to SIOC-enabled datastore is triggered.
The datastore is Storage I/O Control-enabled, but it cannot be fully controlled by Storage I/O Control because of the external workload.
This condition can occur if the Storage I/O Control-enabled datastore is connected to a host that does not support Storage I/O Control.
Ensure that all hosts that are connected to the datastore support Storage I/O Control.