Well interestingly enough I believe the issue was poor benchmarking from the tool I was using.
I did some alternate benchmarking:
- Duplicate large file on same drive
- Use CrystalDisk Mark
The file duplication test, which is both reading and writing to the same drive concurrently, showed substantial speed improvement with BusLogic SCSI.
Crystal Disk Mark results also showed substantial performance gains with SCSI.
BTW, for anyone interested, I initially struggled with the conversion of controller types with a VMDK, but it’s actually really simple.
You don’t need to edit the .vmdk file as suggested by the VMware KB (this usually ends up in an unusable VMDK).
You use qemu-img.
Example: IDE to BusLogic SCSI
qemu-img convert input.vmdk -O vmdk output.vmdk -o adapter_type=buslogic
Then remove the IDE disk and add a SCSI disk for the converted file in your VM settings.
Don’t forget to install the SCSI buslogic driver beforehand so that when you boot the VM, the new SCSI disk can be read.
To see all the different conversion options with qemu-img, use this:
qemu-img convert input.vmdk -O vmdk output.vmdk -o ?
qemu-img is awesome.