I did a vmware-mount on a vmdk file that is on a USB drive. Then I discovered that when I wrote bytes to the virtual drive and read them back, I didn't get the same bytes back. Very bad.
More specifically, I have a large collection of files that are on both a real file system and duplicated on the virtual drive. When I run windiff, comparing the two, it reports a few as not matching. Using Windows Explorer, I copied files from the real drive to the virtual drive. I ran windiff again. They don't match.
Then I unmounted the vmdk, and copied it to my IDE drive. I mounted it there. I ran windiff and got the mismatched files. Then I copied files from the real drive on top of the bad files, and ran windiff again. They match.
I unmounted the vmdk, and copied it back to my USB drive and mounted it. Windiff reports files not equal.
Then I unmounted the vmdk, and copied the vmdk again from the USB to the IDE. I ran windiff on the vmdk files and they are the same. I mounted both vmdks (using different drive letters), and ran windiff agains the two virtual drives and the files did NOT match.
I conclude that I/O to a virtual drive stored on an external USB (2.5") drive is prone to failing silently.
VMware DiskMount Utility version 5.5.0 build-18463
I don't have support, and I think vmware-mount is unsupported software, so I don't know how to tell VMWare about it