I have been mostly using fixed-sized disk images for Oracle virtualbox, but I am considering switching to dynamic disk images as I heard that dynamic images are similar in performance to fixed-size images except when expanding.
One operation I do a lot though is to zero-fill a fixed-size disk image before backing it up using a zip program (to reduce the size of the zip archive). My question is, when I zero-fill a dynamic disk, will the disk size increase to its maximum declared value? (For my specific case, I am using
sdelete -z on windows partitions.)
One additional question is, is there a way to zero-fill partitions without increasing the disk size?
-- EDIT --
To clarify, the reason I ask is that I want to keep the size of compressed virtualbox images at a minimum. Zero-filling a fixed sized image does the job as the zero-filled portion contributes almost nothing to the compressed image. However, if I switch to dynamic disk, zero-filling seems to defeat the purpose of using dynamically sized images.
The second part of my question is really asking if there is a better alternative than zero-filling that can remove unused sectors without expanding the disk size.