6.0.1

Figure 24‑1. Thick and thin virtual disks
VM 2VM 1
40GB
40GB 40GB
80GB
20GB
THICK
THIN
virtual disks
provisioned
capacity
datastore
used
capacity
20GB
40GB
About Virtual Disk Provisioning Policies
When you perform certain virtual machine management operations, such as creating a virtual disk, cloning
a virtual machine to a template, or migrating a virtual machine, you can specify a provisioning policy for the
virtual disk le.
NFS datastores with Hardware Acceleration and VMFS datastores support the following disk provisioning
policies. On NFS datastores that do not support Hardware Acceleration, only thin format is available.
You can use Storage vMotion or cross-host Storage vMotion to transform virtual disks from one format to
another.
Thick Provision Lazy
Zeroed
Creates a virtual disk in a default thick format. Space required for the virtual
disk is allocated when the disk is created. Data remaining on the physical
device is not erased during creation, but is zeroed out on demand at a later
time on rst write from the virtual machine. Virtual machines do not read
stale data from the physical device.
Thick Provision Eager
Zeroed
A type of thick virtual disk that supports clustering features such as Fault
Tolerance. Space required for the virtual disk is allocated at creation time. In
contrast to the thick provision lazy zeroed format, the data remaining on the
physical device is zeroed out when the virtual disk is created. It might take
longer to create virtual disks in this format than to create other types of
disks.
Thin Provision
Use this format to save storage space. For the thin disk, you provision as
much datastore space as the disk would require based on the value that you
enter for the virtual disk size. However, the thin disk starts small and at rst,
uses only as much datastore space as the disk needs for its initial operations.
If the thin disk needs more space later, it can grow to its maximum capacity
and occupy the entire datastore space provisioned to it.
vSphere Storage
270 VMware, Inc.