The answer is simple - when you need it. I can imagine 2 most often use cases: 1. You have a number of VM images and you want to transfer it somethere or backup it on CD/DVD. In that case you should run Parallels VM Compactor for each VM image just once to decrease its transfer/backup overall size. 2. You intensively working with VM image and its size increasing all the time. In that case you should run Parallels VM Compactor on the regular basis. How often? Each time your VM image overgrow comfortable size for you.
. Andrew, If one has a static virtual disk, XPoo installed and a given set of XPoo apps installed, is there an argument for installing Compactor to provide performance gain? .
Technical details So is that what this is? A garbage collector for expandable drives? So the implication is that you, VMWare and Microsof all implement these the same way? Linked lists maybe? Or something like B-Tree? So your compactor walks the list, unlinking stuff no longer used and packing it down? Just seems strange to me that you'd all use the same scheme.. or is it just so easy to figure out that it doesn't matter? Just curious..
Expanding disk starts with no data. When data is written by guest OS it adds allocation block to image file and disk expands. But when guest OS deletes something disk doesn't reduced automatically. VM compressor/compacting tool determines unused allocation blocks and removes it from image file.
