5. vCloud vApp Provisioning : 5.5 Workflow Overview : 5.5.7 Disk Handler
   
5.5.7 Disk Handler
Many organizations require the ability to change their system disk size at deployment time. Although the VCD API does allow for this, and a workflow exists and is incorporated into the sample provided here, it may not be ideal because of the VCD fast provisioning option, which uses linked clones. If fast provisioning is enabled on the virtual datacenter where a vApp is being deployed, and the request specifies resizing the system disk, the workflow is configured to catch the exception generated by the failure to resize the disk, log it, and continue with the next step of the workflow. This piece of the sample workflow uses the Change hard disk capacity VCD Library workflow.
Most virtual machines used as vApp templates have a limited number of base hard disks, where the OS and base applications are installed. A common request has been the ability to add an additional disk at the time of request. The sample workflow has this feature built-in. This piece of the sample workflow uses the Add a hard disk VCD Library workflow. The disk, however, is only presented to the guest OS, it is not partitioned or formatted. This in-guest operation requires additional scripting for the requester to partition and format the new disk as desired.