You can change the disk resources for a virtual machine. If multiple virtual machines access the same VMFS datastore and the same logical unit number (LUN), use disk shares to prioritize the disk accesses from the virtual machines. Disk shares distinguish high-priority from low-priority virtual machines.

You can allocate the host disk's I/O bandwidth to the virtual hard disks of a virtual machine. Disk I/O is a host-centric resource so you cannot pool it across a cluster.

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.


  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.
    • Low (500)
    • Normal (1000)
    • High (2000)
    • 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.