How-to enable PvSCSI and when
VMware Paravirtualized SCSI (PVSCSI driver)
Introduced with vSphere 4 this driver can speed up and offload CPU. VMware Paravirtual SCSI (PVSCSI) adapter is able to achieve 12% more throughput with 18% less CPU cost compared to the LSI virtual adapter.
vSphere ships with this new high performance virtual storage adapter. Bus logic and LSI logic were the only choices so far. PVSCSI is best suited to run highly I/O intensive applications in the guest more efficiently (reduced CPU cycles)
Before you activate and configure take into consideration that:
- VMware does not support PVSCSI on the operating system boot partition, VMs will need to be configured with separate virtual disks(.vmdk) for the boot drive and the data drive. It means that the only way you can use PVSCSI is on your DATA drives.
UPDATE: This is no longer the case. Now VMware supports pvscsi for boot disks. You can have a look here to see an elegant way of changing into pvscsi.
- You can’t use PVSCSI on a VM which is configured for Fault Tolerance protection. (BTW if the VM has FT enabled, it can’t use VMXNET3 either…). See the requirements and limitations of FT here.
The actual step-by-step for Windows you can follow here or Linux here.
Some good read about PVSCSI and separating the Boot and Data partitions you can find on Rich Brambley’s blog as well

For some more documentation and(or) how-to, some more links:
For linux VM:
For Windows VMs:
vSphere Performance whitepaper (VMware)
What’s new in vSphere Storage whitepaper (VMware)
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