When deploying a Provisioning Services environment, the question of where to host the vDisk store and the VHD files for target devices often arises. There are really only two primary options:
1) Block Level Storage
2) NAS Storage (CIFS or in some cases NFS)
I go into quite of a bit of detail as to why one should select block level storage and the benefits of Windows System Cache in reducing disk IOPS associated with Provisioning Server in a white paper I wrote entitled Advanced Memory and Storage Considerations for Provisioning Services. You can check out the White paper here http://support.citrix.com/article/ctx125126. I encourage everyone to first read the white paper as it will help in understanding the rest of this post.