When you perform certain virtual machine management operations, you can specify a provisioning policy for the virtual disk file. The operations include creating a virtual disk, cloning a virtual machine to a template, or migrating a virtual machine.

vSAN forms the storage backbone of VMware Cloud on AWS and vSAN storage polices define storage requirements for the virtual machines. These policies guarantee the required level of service for the VMs because they determine how storage is allocated to the VM.

The default policy contains vSAN rule sets and a set of basic storage capabilities, typically used for the placement of virtual machines deployed on vSAN datastores.



 Primary level of failures to tolerate 


 Number of disk stripes per object


 Flash read cache reservation, or flash capacity   used for the read cache


 Object space reservation


 Note: Setting the Object space reservation to zero means that the virtual   disk is thin provisioned, by default.

 Force provisioning


Object Space Reservation (OSR) determines the percentage of the logical size of the virtual machine disk (vmdk) object that must be reserved, or thick provisioned when deploying virtual machines. The default value is 0% (Thin Provisioning) and maximum value is 100% (Thick Provisioning).

More information about this can be found here..

The below table shows the various vmdk modes, namely dependent, independent-persistent, and independent-non-persistent.







 Dependent disks are included in snapshots.


 Disks in persistent mode behave like conventional disks on your   physical computer. All data written to a disk in   persistent mode is   written permanently to the disk.

 Independent– non-persistent

 Changes to disks in non-persistent mode are discarded when you turn   off or reset the virtual machine. With non-   persistent mode, you can   restart the virtual machine with a virtual disk in the same state every   time. Changes to   the disk are written to and read from a redo log file   that is deleted when you turn off or reset the virtual machine.

More information on Virtual Disk Provisioning Policies can be found here.


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