Re: Changing LSI Logic SAS to Paravirtual controller on Windows 2012 R2?

First you have to add small disk to the same virtual machine from paravirtual adapter.Then it will automatically installed drivers to virtual machine. after that safely you can remove that disk & change your existing disk controllers.

Please follow below steps which is mentioned in vmware kb

To configure an existing Windows boot disk to use a PVSCSI adapter:

This procedure is required as the guest operating system does not have the PVSCSI driver and the guest will BSOD on boot if using the above method. This workaround forces the guest operating system to install the PVSCSI driver.

1. Power off the virtual machine.
2. Create a new temporary 1GB disk(SCSI 1:0) and assign a new SCSI controller (default is LSI LOGIC SAS).
3. Change the new SCSI controller to PVSCSI for the new SCSI controller.
4. Click Change Type.
5. Click VMware Paravirtual and click OK.
6. Click OK to exit the Virtual Machine Properties dialog.
7. Power on the virtual machine.
8. Verify the new disk was found and is visible in Disk Management. This confirms the PVSCSI driver is now installed.
9. Power off the virtual machine.
10. Delete the temporary 1GB vmdk disk and associated controller (SCSI 1:0).
11. Change the original SCSI controller(SCSI 0:X) to PVSCSI as detailed in Steps 3 to 5.
12. Power on the virtual machine.

Configuring disks to use VMware Paravirtual SCSI (PVSCSI) adapters (1010398) | VMware KB