Virtual SAN requires that the virtual machines deployed on the Virtual SAN datastores are assigned at least one storage policy. When provisioning a virtual machine, if you do not explicitly assign a storage policy to the virtual machine the Virtual SAN Default Storage Policy is assigned to the virtual machine.

The default policy contains Virtual SAN rulesets and a set of basic storage capabilities, typically used for the placement of virtual machines deployed on Virtual SAN datastores.

Table 1. Virtual SAN Default Storage Policy Specifications
Specification Setting
Number of failures to tolerate 1
Number of disk stripes per object 1
Flash read cache reservation, or flash capacity used for read cache 0
Object space reservation 0
Note: Setting the Object space reservation to zero means that the virtual disk will be thin provisioned, by default.
Force provisioning No

You can review the configuration settings for the default virtual machine storage policy from the vSphere Web Client when you navigate to the VM Storage Policies > Virtual SAN Default Storage Policy > Manage > Rule-Set 1: VSAN.

For best results, consider creating and using your own VM storage policies, even if the requirements of the policy are same as those defined in the default storage policy. For information about creating a user-defined VM storage policy, see Define a Virtual Machine Storage Policy for Virtual SAN.

When you assign a user-defined storage policy as the default policy to a datastore, Virtual SAN automatically removes the association to the default storage policy and applies the settings for the user-defined policy on the specified datastore. At any point, you can assign only one virtual machine storage policy as the default policy to the Virtual SAN datastore.

Characteristics

The following characteristics apply to the Virtual SAN Default Storage Policy.

  • The Virtual SAN default storage policy is assigned to all virtual machine objects if you do not select any other Virtual SAN policy when you provision a virtual machine, that is when the VM Storage Policy field is set to Datastore default on the Select Storage page. For more information about using storage policies, see the vSphere Storage documentation.
  • The Virtual SAN default policy only applies to Virtual SAN datastores. You cannot apply the default storage policy to non-Virtual SAN datastores, such as NFS or a VMFS datastore.
  • Because the default virtual machine storage policy is compatible with any Virtual SAN datastore in the vCenter Server, you can move your virtual machine objects provisioned with the default policy to any Virtual SAN datastore in the vCenter Server.
  • You can clone the default policy and use it as a template to create a user-defined storage policy.
  • You can edit the default policy, if you have the StorageProfile.View privilege. You must have at least one Virtual SAN enabled cluster that contains at least one host. VMware highly recommends that you do not edit the settings of the default storage policy.
  • You cannot edit the name and description of the default policy, or the Virtual SAN storage provider specification. All other parameters including the policy rules are editable.
  • You cannot delete the default policy.
  • The default storage policy is assigned when the policy that you assign during virtual machine provisioning does not include rules specific to Virtual SAN.