PVSCSI Adapter

Previous versions of ESX emulated BusLogic and LSI Logic storage adapters within the virtual machine. The virtual machine would load a BusLogic or LSI Logic driver within the guest to access the virtual storage adapter. The advantage of this full virtualization is that most operating systems ship drivers for these devices. ESX 4.0 includes a new paravirtualized storage adapter called PVSCSI. This extends to the storage stack the kind of performance gains associated with other paravirtualized devices, such as the VMXNET network adapter available in earlier versions of ESX.

As with other paravirtualized devices, PVSCSI emulation improves efficiency by:

  • Reducing the cost of virtual interrupts
  • Batching the processing of I/O requests
  • Batching I/O completion interrupts

A further optimization, which is specific to virtual environments, reduces the number of context switches between the guest and Virtual Machine Monitor.


About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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