You can implement QOS in OFI, however that really addresses a different issue than SIOC is addressing. When you implment QOS in OFI, you are saying
"If there is contention between the traffic that is coming from different vHBAs to get on to the fibre channel cable from OFI to the Fibre channel switch, then this is how to prioritize the traffic based on the originating vHBA"
However, OFI QOS has no idea what VMs should be getting priority. It doesn't map to VMs, just to vHBAs that presented to the ESXi host. Those vHBAs in our case are common to all VMs on a host. So Oracle QOS doesn't help prioritize one VM over another. VMs on the same host end up sending all their traffic over the same vHBAs.
When you implement SIOC, what you are saying is "These VMs get priority during contention". You are mapping directly to the VMs that are important.
So you cannot use QOS on Oracle Fabric Interconnect as a substitute for SIOC to prioritize VM storage traffic.
OFI QOS has two limitations:
- It doesn't know which VM originated the traffic, only which ESXi vHBA originated it
- It doesn't know anything about the state of the VMware datastore that the traffic is going to. It only knows about the state of a single Fibre Channel cable on route to that datastore. That cable could be one of multiple cables on the Fibre Channel Fabric.
Basically, QOS is managing contention for access to the physical medium at a lower layer than SIOC, which is managing contention at the VM/datastore level.