ok, now it's clear....

Using log file /var/tmp//vmware-markcox/vdiskmanager.log
Failed to defragment: There is not enough space on the file system for the selected operation (14).

Does the above message refer to enough space on the virtual drive, or on the Mac HD...

Can you use vdiskmanager to expand te disk when the vm is suspended... or are you supposed to shut it down first...

Well how much space would the Mac HD need... I read that windows likes 20% free space... is that the same for the Mac....

PS. I booted from an external drive.. and cannot unmount my internal Mac HD... which I was trying to do for iDefrag...

You might want to see. It may work in that case, but I don't recommend doing that to begin with because the suspend state is based upon the state of a known setup when suspended.

Pat

I have an unallocated vdisk... and despite the recommended steps.. I couldn't use vdiskmanager prior to using iDefrag... after using iDefrag I was then able to use vdiskmanager. I had already used diskeeper prior to using either... and after using vdiskmanager, another run of using iDefrag didn't do any further defragmenting... but keep in mind that with iDefrag I was only doing the Quick (on-line) Defrag because for some reason I couldn't unmount the Mac HD (when booted from an external drive) to do the Full Defrag..

I do see a continuous chunk of blank space following what appears to be a large red chunk... so I assume this is an area of the yet unallocated vdisk...

There is still a good deal of red space...

I would like to shrink a virtual disk. How do I do that?

Why would anyone ever wanna do that? Well... when
I created the virtual disk, the host drive had sufficient
space to hold it (if it were to ever fill up). However, by
now two things have happened: first, the host disk is
getting filled up with other stuff, and second, it looks
like I won't be needing as large a virtual disk after all.

Therefore I'd link to shrink the virtual disk, to prevent
the scenario in which it would (fill up and) not fit onto
the host disk -- which kinda gives me the creeps... :-o

Fwiw, the virtual disk in question is stored in 2G files,
most of which haven't reached 2G yet -- so if I'm not
mistaken, then it's of type 1 (vmware-vdiskmanager).

Also, I am capable of shrinking the partition that is in
said virtual disk (or so I believe -- I'd have to defrag it
before using e.g. Partition Magic... but I'm worried that
defragmenting it [in the VM] will cause all 2G chunks
to be allocated, i.e. I'd run out of host disk space).

I know about the "defrag and then eliminate the zeros, to
shrink the virtual disk" option. However, I was looking for
something else; namely the ability to shrink a virtual disk.
That is, defrag the guest, shrink its partition, and then do
a shrink of the virtual disk.

In essence a reverse of the "grow a virtual disk, then grow
the partition inside it" path.