I have seen this discussed a few times through the years. People say that it shouldn't make a difference but has anyone actually tested it? I have two VMs and they have files for their HD image, not dedicated partition. When defragmenting the disk (yes macs DO get fragmentation despite people not wanting to believe in it) one of the VM's virtual disk was split in over 9000 chunks and the other a bit over 4000 chunks. They were the most fragmented files in the whole system. Now these VMs run visual studio and are used to compile code all the time so it may not be a typical usage pattern, but 9000 chunks is crazy and performance can't be good. So I am going to try to install the images on dedicated partitions; but now another question pops up: when the image is a file, even if heavily fragmented, the io goes through OSX's file API so memory that is not allocated is used as a disk cache. By moving to a dedicated partition there is a chance that this will not be the case, possibly hurting performance. Does anyone have any insight on this? Also, does anyone know how to turn a virtual HD into a partition?
