- MacBookPro retina (mid-2015, model 11,5) running OSX 10.11.6.
- External USB3 HD, NTFS formatted, into which I installed Windows 10 [1]. EFI mode was required for that.
- Hard drive can boot the MBPr externally and the Mac runs Windows 10 just fine (unavoidable, necessary evil, please don't accuse me of treason ).
- Hard drive can also be accessed via the "rawdisk" option and run as a VM in OSX with VirtualBox 5.2.0. With the GAs installed and everything working great [2].
- Finally, the HD can be accessed as a plain old ext. HD. OSXFuse with NTFS-3g used, with no write caching.
So, if I simply mount the NTFS formatted USB3 ext. HD, I get the maximum of 85 MB/s (=680 Mb/s), which proves that I can have more than USB2 speeds (max. theor. 480 Mb/s). Not the theoretical 5120 Mb/s (just a 13.3% of that), but at least it's something.OSX to USB3 mounted as a disk (Finder) ........ : 680 Mb/s <-- That's more than USB 2. Win10 booting natively, file duplication ...... : 360 Mb/s <-- Unacceptable. OSX to USB3 mounted as a disk (cp) ............ : 240 Mb/s <-- Finder vs. 'cp': What??? Win10 as a VM, guest from VBox shared folder .. : 120 Mb/s Win10 as a VM, internal copy .................. : 55 Mb/s <-- Has to go through the host twice. Win10 as a VM, guest from SMB network share ... : 40 Mb/s <-- ??????
On the other hand, if I boot from the ext. HD to a native Win10 environment, the speeds drop really, really low to 360 Mb/s. And I refer to really low as in compared to the 5120 Mb/s. Even with half that I'd be happy, but not at a measly 7% performance.
At the beginning I thought that it might be something to do with how the natively boot Win10 sees the USB port (or it is presented to it by the MBPr ). Maybe it sees it / it is presented as a USB2 one. That's a potential thing to consider, but alas, all the signs in Win10 show that it is recognized as a USB3 HD on a USB3 port. Nothing else connected BTW, straight to the source. Oh, and I tried both ports on the MBPr.
Of course I can gather any information that might be suitable, I simply didn't want to flood the post with too much information. I'll start with some basics and if anyone has any need to see something more, feel free to ask...
[1]: I can provide the details (sweat, blood and tears) that this required, but not on this post, it's going to be too long. Just ask. And yes, it does involve VirtualBox...
[2]: Do NOT install the Win10 updates while running the whole setup in a VM. It's an old known bug (#1633). And it's a pain to recover from that...