Allocate storage I/O resources to virtual machines based on importance by assigning a relative amount of shares to the virtual machine.

Unless virtual machine workloads are very similar, shares do not necessarily dictate allocation in terms of I/O operations or megabytes per second. Higher shares allow a virtual machine to keep more concurrent I/O operations pending at the storage device or datastore compared to a virtual machine with lower shares. Two virtual machines might experience different throughput based on their workloads.


See vSphere Storage for information on creating VM storage policies and defining common rules for VM storage policies.


  1. Browse to the virtual machine in the vSphere Client.
    1. To find a virtual machine, select a data center, folder, cluster, resource pool, or host.
    2. Click the VMs tab.
  2. Right-click the virtual machine and click Edit Settings.
  3. Click the Virtual Hardware tab and select a virtual hard disk from the list. Expand Hard disk.
  4. Select a VM storage policy from the drop-down menu.
    If you select a storage policy, do not manually configure Shares and Limit - IOPS.
  5. Under Shares, click the drop-down menu and select the relative amount of shares to allocate to the virtual machine (Low, Normal, or High).
    You can select Custom to enter a user-defined shares value.
  6. Under Limit - IOPS, click the drop-down menu and enter the upper limit of storage resources to allocate to the virtual machine.
    IOPS are the number of I/O operations per second. By default, IOPS are unlimited. You select Low (500), Normal (1000), or High (2000), or you can select Custom to enter a user-defined number of shares.
  7. Click OK.