When you create a virtual disk, you can specify disk properties, such as size, format, clustering features, and more. However, the most important property is the format.

The type of virtual disk used by your VM can have an effect on the I/O performance; thus, it plays a vital role in maintaining disk performance. The type of disks that are available today are:

• Thick provision eager zeroed
• Thick provision lazy zeroed
• Thin provision

You need to carefully evaluate the workload and the performance factors of each disk before you choose one.