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 Datastore.
Which action would mitigate the issue?
Enable Storage IO Control.
Configure Storage DRS.
Enable the Dynamic Queue Depth Throttling option.
Configure the Disk.SchedNumReqOutstanding parameter.
SIOC is extremely powerful, it can increase your consolidation ratios on the storage side, allowing more VM’s per datastore. Which leads to lower storage costs and less administrative overhead.
So how does it work? At a basic level SIOC is monitoring the end to end latency of a datastore. When there is congestion (the latency is higher than the configured value) SIOC reduces the latency by throttling back VM’s who are using excessive I/O. Now you might say, I need that VM to have all of those I/O’s, which in many cases is true, you simply need to give the VMDK(s) of that VM a higher share value. SIOC will use the share valuesassigned to the VM’s VMDK’s to prioritize access to the datastore.
Just simply turning SIOC on will guarantee each VMDK has equal access to the datastore, shares fine tune that giving you the ability to give VMDK’s more or less priority during times of contention.