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1.4 – Differentiate between vSphere Network I/O Control (NIOC) and vSphere Storage I/O Control (SIOC)

NIOC is used for QoS on network traffic and is useful for vSAN when it shares the physical NIC with other traffic types. 

  • Reserves bandwidth for system traffic based on the capacity of the physical adapters on a host. 
  • Enabled fine-grained resource control at the VM network adapter level similar to the model that you use for allocating CPU and memory resources.
  • You can enable it on a vSphere distributed switch to guarantee minimum bandwidth to system traffic for vSphere features and to virtual machine traffic. 
  • You can allocate bandwidth for traffic generated by vSphere Fault Tolerance, vSphere vMotion and so on.
  • You can allocate bandwidth requirements for individual virtual machines and use network resource pools where you can assign a bandwidth quota from the aggregated reservation for the VM traffic. 
  • You can exclude physical adapters from the bandwidth allocation model 
  • You’ll need an enterprise plus license.

It divides the traffic into resource pools and bandwidth reservations can be used to isolate network resources for a class of traffic. 

There are several models for bandwidth resource reservation. 

  • System Traffic: configure shares, reservations and limits.
  • Management, Fault Tolerance, NFS, vSAN, vMotion, vSphere replication, vSphere data protection backup, Virtual Machine.
  • Network Resource Pools: Controls the VM traffic.
  • Bandwidth Guarantee to VMs: each VM stays connected by the definition of the amount of shares.
  • Shares will be used on a scale from 1 to 100 to reflect the priority of a system traffic type against other system traffic types.  
  • The reservation will guarantee a minimum amount of bandwidth, in Mbps, for a single physical NIC. It cannot exceed 75% of the bandwidth available of the lowest capacity NIC.  
  • A limit sets the maximum bandwidth, in Mbps or Gbps that a system traffic type can consume.

SIOC prevents VMs from being the “noisy neighbor” situation where a single VM takes up all the resources. The latency is monitored and if this is higher than the configured values, SIOC kicks in and reduces the latency by throttling back VMs that are exceeding their consumption of IOPS. 

It only kicks in when there is contention and makes sure that each VM gets their fair share of storage resources. 

  • Is supported on Fiber Channel, iSCI, NFS connected storage 
  • Does not support datastores with multiple extents
  • SAN with auto-tiering has to be certified for SIOC 
  • Datastores that are SIOC enabled must be managed by a single vCenter Server system 
  • Must be disabled before removing a datastore 
  • Raw Device Mapping is not supported