vSphere Storage - ESXi 5.1 - Documentation - VMware

vSphere Storage
2 Double-click the virtual machine.
3 Click the Related Objects tab and click Datastores.
The datastore that stores the virtual machine files is listed.
4 Click the datastore link to open the datastore management panel.
5 Click the Manage tab and click Files.
6 Open the virtual machine folder and browse to the virtual disk file that you want to convert.
The file has the .vmdk extension and is marked with the virtual disk ( ) icon.
7 Right-click the virtual disk file and select Inflate.
The inflated virtual disk occupies the entire datastore space originally provisioned to it.
Handling Datastore Over-Subscription
Because the provisioned space for thin disks can be greater than the committed space, a datastore oversubscription
can occur, which results in the total provisioned space for the virtual machine disks on the
datastore being greater than the actual capacity.
Over-subscription can be possible because usually not all virtual machines with thin disks need the entire
provisioned datastore space simultaneously. However, if you want to avoid over-subscribing the datastore,
you can set up an alarm that notifies you when the provisioned space reaches a certain threshold.
For information on setting alarms, see the vCenter Server and Host Management documentation.
If your virtual machines require more space, the datastore space is allocated on a first come first served basis.
When the datastore runs out of space, you can add more physical storage and increase the datastore.
See Increase VMFS Datastores.
Array Thin Provisioning and VMFS Datastores
You can use thin provisioned storage arrays with ESXi.
Traditional LUNs that arrays present to the ESXi host, are thick-provisioned. The entire physical space needed
to back each LUN is allocated in advance.
ESXi also supports thin-provisioned LUNs. When a LUN is thin-provisioned, the storage array reports the
LUN's logical size, which might be larger than the real physical capacity backing that LUN.
A VMFS datastore that you deploy on the thin-provisioned LUN can detect only the logical size of the LUN.
For example, if the array reports 2TB of storage while in reality the array provides only 1TB, the datastore
considers 2TB to be the LUN's size. As the datastore grows, it cannot determine whether the actual amount of
physical space is still sufficient for its needs.
However, when you use the Storage APIs - Array Integration, the host can integrate with physical storage and
become aware of underlying thin-provisioned LUNs and their space usage.
Using thin provision integration, your host can perform these tasks:
n Monitor the use of space on thin-provisioned LUNs to avoid running out of physical space. As your
datastore grows or if you use Storage vMotion to migrate virtual machines to a thin-provisioned LUN,
the host communicates with the LUN and warns you about breaches in physical space and about out-ofspace
conditions.
n Inform the array about the datastore space that is freed when files are deleted or removed from the
datastore by Storage vMotion. The array can then reclaim the freed blocks of space.
NOTE ESXi does not support enabling and disabling of thin provisioning on a storage device.
230 VMware, Inc.