An administrator observes that virtual machine storage activity on an ESXi 6.x host is negatively affecting virtual machine storage activity on another host that is accessing the same VMFS…

SIOC enforces I/O share-based fairness at the datastore level by detecting when aggregate latency exceeds a configured threshold and then throttling VM I/O according to assigned shares across all ESXi hosts accessing that datastore. This directly addresses the problem of one host's VM workload degrading storage performance for VMs on another host sharing the same VMFS datastore.

Storage DRS balances VM placement and migration across datastores based on capacity and I/O load, but does not throttle active I/O between competing hosts in real time.

Dynamic Queue Depth Throttling adjusts the queue depth on a per-host basis when a single device reports latency, but it does not coordinate fairness across multiple hosts accessing a shared datastore.

Disk.SchedNumReqOutstanding limits the number of outstanding I/O requests per datastore on a single host but provides no cross-host coordination or fairness enforcement.