6.7

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 later on
first 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. Increasing the size of an Eager Zeroed Thick virtual disk causes a
significant stun time for the virtual machine.
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
first, 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.
Thin provisioning is the fastest method to create a virtual disk because it
creates a disk with just the header information. It does not allocate or zero
out storage blocks. Storage blocks are allocated and zeroed out when they
are first accessed.
Note If a virtual disk supports clustering solutions such as Fault Tolerance,
do not make the disk thin.
Large Capacity Virtual Disk Conditions and Limitations
Virtual machines with large capacity virtual hard disks, or disks greater than 2 TB, must meet resource
and configuration requirements for optimal virtual machine performance.
The maximum value for large capacity hard disks is 62 TB. When you add or configure virtual disks,
always leave a small amount of overhead. Some virtual machine tasks can quickly consume large
amounts of disk space, which can prevent successful completion of the task if the maximum disk space is
assigned to the disk. Such events might include taking snapshots or using linked clones. These
operations cannot finish when the maximum amount of disk space is allocated. Also, operations such as
snapshot quiesce, cloning, Storage vMotion, or vMotion in environments without shared storage, can take
significantly longer to finish.
Virtual machines with large capacity disks have the following conditions and limitations:
n
The guest operating system must support large capacity virtual hard disks.
vSphere Virtual Machine Administration
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