I mean Storage I/O Control (SIOC), but note that Storage DRS uses SIOC too. Take a look at this KB article: VMware KB: Unmanaged I/O workload detected on shared datastore running Storage I/O Control (SIOC) for congestion man…
This informational event alerts the user of a potential misconfiguration or I/O performance issue caused by a non-ESX workload. It is triggered when Storage I/O Control (SIOC) detects that a workload that is not managed by SIOC is contributing to I/O congestion on a datastore that is managed by SIOC. (Congestion is defined as a datastore's response time being above the SIOC threshold.) Specific situations that can trigger this event include:
- The storage array is performing a system operation such as replication or RAID reconstruction.
- VMware Consolidated Backup or vStorage APIs for Data Protection are accessing a snapshot on the datastore for backup purposes.
- The storage media (spindles, SSD) on which this datastore is located is shared with volumes used by non-vSphere workloads
- The host is running in an unsupported configuration.