6.7

How Storage Controller Technology Works
Storage controllers appear to a virtual machine as different types of SCSI controllers, including BusLogic
Parallel, LSI Logic Parallel, LSI Logic SAS, and VMware Paravirtual SCSI. AHCI, SATA, and NVMe
controllers are also available.
When you create a virtual machine, the default controller is optimized for best performance. The controller
type depends on the guest operating system, the device type, and sometimes, the virtual machine's
compatibility. For example, when you create virtual machines with Apple Mac OS X guests and ESXi 5.5
and later compatibility, the default controller type for both the hard disk and the CD/DVD drive is SATA.
When you create virtual machines with Windows Vista and later guests, a SCSI controller is the default
for the hard disk and a SATA controller is the default for the CD/DVD drive.
In high performance storage environments you can benefit from using VMware Paravirtual SCSI
controllers. The VMware Paravirtual SCSI controller ensures greater throughput and lower CPU use,
which boosts performance as compared to the other SCSI controller options. For platform support for
VMware Paravirtual SCSI controllers, see the VMware Compatibility Guide at
http://www.vmware.com/resources/compatibility.
Each virtual machine can have a maximum of four SCSI controllers and four SATA controllers. The
default SCSI or SATA controller is 0. When you create a virtual machine, the default hard disk is assigned
to the default controller 0 at bus node (0:0).
When you add storage controllers, they are numbered sequentially 1, 2, and 3. If you add a hard disk,
SCSI, or CD/DVD-ROM device to a virtual machine after virtual machine creation, the device is assigned
to the first available virtual device node on the default controller, for example (0:1).
If you add a SCSI controller, you can reassign an existing or new hard disk or device to that controller. For
example, you can assign the device to (1:z ), where 1 is SCSI controller 1 and z is a virtual device node
from 0 to 15. For SCSI controllers, z cannot be 7. By default, the virtual SCSI controller is assigned to
virtual device node (z:7), so that device node is unavailable for hard disks or other devices.
If you add a SATA controller, you can reassign an existing or new hard disk or device to that controller.
For example, you can assign the device to (1:z ), where 1 is SATA controller 1 and z is a virtual device
node from 0 to 29. For SATA controllers, you can use device nodes 0 through 29, including 0:7.
Alternatively, each virtual machine can have a maximum of four NVMe controllers. You can reassign an
existing or new hard disk or device to that controller. For example, you can assign the hard disk to (x:z ),
where x is NVMe controller and z is a virtual device node. x has values from 0 to 3, and z has values from
0 to 14.
Storage Controller Limitations
Storage controllers have the following requirements and limitations:
n
LSI Logic SAS and VMware Paravirtual SCSI are available for virtual machines with ESXi 4.x and
later compatibility.
n
Virtual machines with VMware Paravirtual SCSI controllers cannot be part of an MSCS cluster.
vSphere Virtual Machine Administration
VMware, Inc. 113