Which is the best type of SCSI controller to use and why? VMware’s best practice for selecting SCSI controllers for your VM is to use the default SCSI controller that VMware selects for you.
Why is this? Well, each yupe of SCSI controller in VMware works best with different operating systems (with one exception that I’ll explain shortly). This is why, when creating a new VM, VMware will ask you what operating system you plan to use; It will then assign the default virtual hardware that works best with that operating system, which includes the best type of SCSI controller to use with that operating system.
Here is a list of SCSI controllers available to VMs and the operating systems they work with:
BusLogic Parallel – Works with operating systems prior to Windows 2000
LSI Logic Parallel – Works with Windows Server 2000 and 2003
LSI Logic SAS – Works with Windows Server 2008 and above
As you can see, each type of SCSI controller is designed to work with each Windows operating system. There is however, a 4th type of SCSI controller called VMware Paravirtual. The VMware Paravirtual SCSI controller is a special SCSI controller that is designed to be used for disks that require a very high amount of IOps (lots of data traffic) – more than 2000 IOps.
So why not always use the VMware Paravirtual SCSI controller if it’s faster? Well, firstly this SCSI controller doesn’t support spanned disks (It’s supported, but you can lose data because of the way Windows works). Secondly, it requires VMware Tools to be installed on the server. Why is this a problem? If there’s a problem with VMware Tools, you won’t be able to boot your VM. Also, it makes it harder to install Windows because it’s the only type of SCSI controller that doesn’t have drivers in Windows by default.