Lately I’ve been looking into virtualizing latency sensitive applications like the ones used in a lot of financial institutions. In vSphere 6 and below, configuring SR-IOV to hardware accelerate network traffic for latency sensitive VM’s would limit the vSphere features per the SR-IOV Support documentation. This is also true with DirectPath I/O. However, the good news is that vSphere 7 has a new feature called Assignable Hardware that has two consumers; The new Dynamic DirectPath I/O and NVIDIA vGPU. Dynamic DirectPath I/O helps by providing the same functionality as ‘legacy’ DirectPath I/O, but does not pin a workload/VM to a host. This brings back HA and DRS Initial placement to VM’s configured for latency sensitive applications. vMotion is not supported because vSphere cannot live migrate a VM that is directly tied to a physical device. SR-IOV devices are also supported by Assignable Hardware when used as pure passthrough devices.
The VMware High Performance Compute team has been working with our vSphere development teams to bring more capabilities to high performance compute and latency sensitive virtualized workloads without sacrificing bare metal performance.
For more details on Assignable Hardware, check out:
vSphere 7 – Assignable Hardware
vSphere 7 – Using Assignable Hardware with Dynamic DirectPath IO
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