How does shrink with vmware disk manager work?
I found the explanation below on the invirtus site to be the simplest. One of the side-effects of shrinking VMDK files with this approach is that with sparse files it will actually increase the size of the file as the filler files are created and then decrease it. So if you are very close to full capacity on your hard drive this may not be the best option.
VMware® disk types are files with the extension .vmdk (dot vmdk). Shrinking vmdk files (shrink vmdk) can be accomplished with VMware’s built-in VMware Tools. VMware Tools has a shrink facility built-in which can be used on a dynamically expanding disk type (disk space is not pre-allocated for this virtual disk type and can be reclaimed). To do so go to the Windows Control Panel, open VMware Tools then click the Shrink tab.
Shrinking is a two-step procedure.
Step 1: When you click “Prepare to shrink” the tools utility launches a program which fills the free-space on the entire disk with zero filled files named wiper0, wiper1, wiper2, etc, until the entire disk is filled. These “wiper” files are then deleted at the conclusion of the process and the free-space is reclaimed.
Step 2: At the conclusion of shrink preparation you will be presented with a dialog which asks if you would like to shrink your disk(s). If you answer yes to this prompt VMware Tools essentially creates a new disk with the same partition characteristics as the existing disk and simply writes contents of the existing disk into the new disk and at the conclusion of the process it deletes the old disk, renames the new disk and makes it current.
VM Optimizer relies on step 2 for its final procedure but adds hundreds of additional methods to the first step. The result is that when shrinking your vmdk file VM Optimizer will give you the smallest possible virtual machine.