6.0

Shares is a value that represents the relative metric for controlling disk bandwidth to all virtual machines.
The values are compared to the sum of all shares of all virtual machines on the server.
Disk shares are relevant only within a given ESXi host. The shares assigned to virtual machines on one host
have no effect on virtual machines on other hosts.
You can select an IOP limit, which sets an upper bound for storage resources that are allocated to a virtual
machine. IOPs are the number of I/O operations per second.
Procedure
1 In the vSphere Client inventory, right-click the virtual machine and select Edit Settings.
2 Click the Resources tab and select Disk.
3 In the Resource Allocation panel, select the virtual hard disk to change.
4 Click the Shares column and change the value to allocate a number of shares of its disk bandwidth to
the virtual machine.
n
Low (500)
n
Normal (1000)
n
High (2000)
n
Custom
When you select a shares symbolic value, the numeric value appears in the Shares Value column. You
can select Custom to enter a user-defined shares value.
5 Click the Limit - IOPS column and enter the upper limit of storage resources to allocate to the virtual
machine.
6 Click OK to save your changes.
SCSI and SATA Storage Controller Conditions, Limitations, and
Compatibility
To access virtual disks, CD/DVD-ROM, and SCSI devices, a virtual machine uses storage controllers, which
are added by default when you create the virtual machine. You can add additional controllers or change the
controller type after virtual machine creation. You can make these changes while you are in the creation
wizard. If you know about node behavior, controller limitations, and compatibility of different types of
controllers before you change or add a controller, you can avoid potential boot problems.
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 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 in some cases, 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.
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).
Chapter 15 Configuring Virtual Machines in the vSphere Client
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