USB3 implementation MacPro Tube vs MBP Retina

[Gary Huff]

[Craig Seeman] “Interesting limitation. All USB3 ports on single PCIe lane on MacPro.
MBP has one port per line.”

The USB3 ports were probably intended to be used for any wired input accessories, external optical drives, and the occasional need for a 5,200k portable drive that you might need to hook up to pull data from.

Which is why there are only four.

[Craig Seeman]

[Gary Huff] “Which is why there are only four.”

The issue is not that there are only four but that all for are on only one PCIe lane.
The MBP Retina only has two but each are one their own PCIe lane.

Two lanes on Retina
One lane on MacPro.
Retina will have better performance on USB3 RAIDs. Retina can use two devices on separate buses for maximum throughput.

[Tom Sefton]

interesting.

I’m not aware of any USB3.0 RAIDs that have more than 2 hard drives, but the external SSD is an annoyance. We’ve got a couple of USB 3.0 docks that we use to transfer data from Blackmagic Camera SSD’s. Sounds like this could double the amount of time it takes to transfer data from a full card from what it has been doing with our Retina MBPs.

[Craig Seeman]

[Tom Sefton] “I’m not aware of any USB3.0 RAIDs that have more than 2 hard drives, “

Mercury Elite Pro Qx2 can do USB3 RAID.
https://eshop.macsales.com/shop/hard-drives/RAID/Desktop/

Although I was thinking of using it just for JBOD purposes. OWC said Thunderbay IV would be more appropriate for JBOD use as well as JBOD and RAID combination.
https://eshop.macsales.com/shop/Thunderbolt/External-Drive/OWC/ThunderBay-IV

[Tom Sefton]

Nice – those things look good.

Tricky to import to the UK, but after pleading ignorance and bothering to search in google I can see there are some nice LaCie ones out there too.

A strange move from apple then.

[Paul Dickin]

[Tom Sefton] “A strange move from apple then.”
Hi
Blame it on Intel:
https://images.anandtech.com/reviews/mac/MacPro2013/MPsystemarch_north.png
https://images.anandtech.com/reviews/mac/MacPro2013/MPsystemarch_south.png
Or they could have eliminated the GigE and WiFi…

[Chris Kenny]

[Craig Seeman] “Mercury Elite Pro Qx2 can do USB3 RAID.
https://eshop.macsales.com/shop/hard-drives/RAID/Desktop/“

But you’d need to hook up at least two of them and do simultaneous data access in the same direction across both of them before you’d feel the difference between one PCIe lane for all the ports and one PCIe lane per port. Actually, even that might not do it. Those units benchmark below 200 MB/s each over USB 3. At that data rate you’d need three of them, with simultaneous data access in the same direction across all three, before you’d be bottlenecked by that 500 MB/s PCIe lane.

That’s a pretty contrived situation. In general, Apple knew they’d need to accept bottlenecks in some places given the number of PCIe lanes available from the CPU and the chipset… and they were pretty smart about locating those bottlenecks so they’d cause the fewest compromises in real-world performance.

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[Craig Seeman]

So while doing a live stream one is recording ProRes 422 1080p29.97 on one drive, playing back a ProRes 422 clip on another, using a Magewell SDI to USB3 device for HD camera in doing a Picture in Picture with the clip. I think that might be pushing things far. Based on the above info that might be easier to do on a 15″ MBPRetina. Just saying…

[Eric Santiago]

Maybe with the Mac Pro the intention was simple since you have plenty of other ports.
The rMBP is limited so why not give each a dedicated lane.

[Gary Huff]

[Craig Seeman] “Just saying…”

So you don’t really mean that?