Configuring disks to use VMware Paravirtual SCSI (PVSCSI) adapters

Configuring disks to use VMware Paravirtual SCSI (PVSCSI) adapters


Details

This article includes supplemental information about configuring and using VMware Paravirtual SCSI (PVSCSI) adapters.
PVSCSI adapters are high-performance storage adapters that can result in greater throughput and lower CPU utilization. PVSCSI adapters are best suited for environments, especially SAN environments, where hardware or applications drive a very high amount of I/O throughput. PVSCSI adapters are not suited for DAS environments.
Paravirtual SCSI adapters are supported on the following guest operating systems:
  • Windows Server 2008
  • Windows Server 2003
  • Red Hat Enterprise Linux (RHEL) 5

Paravirtual SCSI adapters also have the following limitations:

  • Hot add or hot remove requires a bus rescan from within the guest.
  • Disks with snapshots might not experience performance gains when used on Paravirtual SCSI adapters or if memory on the ESX host is overcommitted.
  • If you upgrade from RHEL 5 to an unsupported kernel, you might not be able to access data on the virtual machine's PVSCSI disks. You can run vmware-config-tools.pl with the kernel-version parameter to regain access.
  • Because the default type of newly hot-added SCSI adapter depends on the type of primary (boot) SCSI controller, hot-adding a PVSCSI adapter is not supported.

Solution

To configure a disk to use a PVSCSI adapter:
  1. Launch a vSphere Client and log in to an ESX host system.
  2. Select a virtual machine, or create a new one.
  3. Ensure a guest operating system that supports PVSCSI is installed on the virtual machine.

    Note: Booting from a disk attached to a PVSCSI adapter is not supported. The system software must be installed on a disk attached to an adapter that does support bootable disk.

  4. In the vSphere Client, right-click on the virtual machine and click Edit Settings.
  5. Click the Hardware tab.
  6. Click Add.
  7. Select Hard Disk.
  8. Click Next.
  9. Choose any one of the available options.
  10. Click Next.
  11. Specify the options your require. Options vary depending on which type of disk you chose.
  12. Choose a Virtual Device Node between SCSI (1:0) to SCSI (3:15) and specify whether you want to use Independent mode.
  13. Click Next.
  14. Click Finish to finish the process and exit the Add Hardware wizard. A new disk and controller are created.
  15. Select the newly created controller and click Change Type.
  16. Click VMware Paravirtual and click OK.
  17. Click OK to exit the Virtual Machine Properties dialog.
  18. Power on the virtual machine.
  19. Install VMware Tools. VMware Tools includes the PVSCSI driver.
  20. Scan and format the hard disk.
Note: In some operating system types, to perform this procedure, you need to create a virtual machine with the LSI controller, install VMware Tools, then change to the drives to paravirtualized mode.
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