Defragmenting virtual hard disks to improve performance
Do I need to defragment virtual hard disks on the host or the guest server to
improve performance, or both?
This depends on how you have things configured. A virtual hard disk file can get fragmented
like any other file, so the best tactic is to not have to defragment it. If you are using a virtual
hard disk file for the guest operating system, defragment the system first before creating it so
you won't have to defragment the file itself later. However, if you're dedicating an entire
physical drive or partition to a given virtual operating system -- which is the best option as far
as performance goes -- then all the defragmentation will take place inside the virtual operating
If you link a virtual disk to a physical disk, this will improve performance and will also
eliminate any problems with the virtual hard disk file growing fragmented. You will still need to
perform any needed defragmentation on the guest operating system's hard disk from within the guest
operating system though.
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This was first published in May 2006