VMware VROOM! Blog

Paravirtualized SCSI (PVSCSI) is a high-performance storage adapter available in VMware vSphere 4. The PVSCSI adapter is best-suited for virtual machines that run applications which generate heavy I/O.

The vSphere 4 performance study compares the performance of PVSCSI with LSI Logic for Fibre Channel and software iSCSI protocols. The experiments show that PVSCSI greatly improves CPU efficiency and improves throughput when the workload drives very high I/O rates. For Fibre Channel, the test results show that PVSCSI reduces the CPIO by 10%-30%. For iSCSI, PVSCSI reduces the CPIO by up to 25%.

Normalized CPIO for Fibre Channel (lower is better)

To read the full study, go to http://www.vmware.com/pdf/vsp_4_pvscsi_perf.pdf. To learn how to configure disks to use the PVSCSI adapter, see http://kb.vmware.com/kb/1010398. For one workload exception where LSI Logic is better, see http://kb.vmware.com/kb/1017652.