Why is my USB 3.0 drive running at USB 2.0 speeds?

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Kai Staats Author

Level 1

0 points

Why is my USB 3.0 drive running at USB 2.0 speeds?

(data for visual reference)

USB 1.1 - 12 Mbit/s

USB 2.0 - 480 Mbit/s

USB 3.0 - 5 Gbit/s

SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s

SATA revision 2.0 - 3 Gbit/s - 300 MB/s

SATA revision 3.0 - 6 Gbit/s - 600 MB/s

When COPYING (not updating) large volumes of data from my internal Segate SATA-III Hybrid drive to an external Seagate USB 3.0 drive, this is what is happening:

Both using OSX
Both data COPY (not updating / integration)
rsync (terminal interface) - 50MB/s transfer or 480Mbit/s (exact USB 2.0 speeds)
copy (desktop drag-n-drop) - 1GB every 15-18 seconds (again, exact USB 2.0 speeds)

1GB * 8 = 8Gbit / 15 = 533,333,333 or about 500Mbit/s

1GB * 8 = 8Gbit / 18 = 444,444,444 or about 444Mbit/s

[So, what I have read about rsync -vs- cp is true -- they are identical for fresh copies.]

But this means that either Seagate or Apple is lying about supporting USB 3.0. I read a report in Feb 2012 that while Apple claims to support USB 3.0, they have not enabled the driver to force people to upgrade to Thunderbolt adapters. Did this change with the Summer 2012 and new models?

The ABOUT THIS MAC profile says my USB 3.0 devices are enabled to transfer up to 5GB/s, but clearly, they are running at EXACTLY USB 2.0 speeds.

Even if the Seagate external drive is just SATA-I, then it should be able to deliver 1.2Gbit/s -- 3x what I am seeing! The fact that the speeds are EXACTLY USB 2.0 tells me the MacBook Pro, while claiming USB 3.0 speeds is nothing more than a USB 2.0 port.

Can someone explain what is happening?

kai

MacBook Pro, Mac OS X (10.7.5)

Posted on Jan 30, 2013 3:07 AM

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Answer 1

dominic23

Level 10

83,904 points

Jan 30, 2013 3:33 AM in response to Kai Staats

More on this:

http://support.apple.com/kb/HT5172

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Answer 2

Kai Staats Author

Level 1

0 points

Jan 30, 2013 3:54 AM in response to dominic23

Thank you Dominic for your quick response. But I had already reviewed this page and it does not solve my problem. The ABOUT THIS MAC info says the drives are connecting at a maximum potential of 5Gbit/s and they do reside on the USB 3.0 interface (as compared to my HP Speakers or mouse which connect at USB 2.0 speeds).

Ideas?

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Answer 3

cbs20

Level 4

2,796 points

Jan 30, 2013 5:38 AM in response to Kai Staats

Which MacBook Pro do you have?

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Answer 4

Kai Staats Author

Level 1

0 points

Jan 30, 2013 5:48 AM in response to cbs20

MacBookPro9,1

"Mid 2012"

purchased in June 2012

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Answer 5

Apr 9, 2014 12:56 PM in response to Kai Staats

I am having the exact same issue on my 2013 MBPr.

I have two Seagate GoFlex USB 3.0s, one plugged into the regular 3.0 port (450MB/s) on the left and the other plugged into the high-speed (5GB/s) 3.0 port on the right. When doing a simple copy/paste from the one drive to the other, I observe the following speeds:

Peak Read (USB 3.0): 36.2Mb/s (288Mbit/s)

Peak Write (USB-HS 3.0): 48.7Mb/s (384Mbit/s)

This is far below the 620MB/s for 3.0 and is more around the 35MB/s USB 2.0 standard.

So, I'm likely to agree with the original compaintant that the 3.0 standards aren't being employed by the MacOSX USB drivers and I'd hope to see a fix soon for these issues lest people start moving off of the Mac platforms to other vendors who adhere to industry guidelines.

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Answer 6

mzew

Level 1

0 points

Aug 7, 2015 2:47 AM in response to Kai Staats

Hi there,

I have the same issue on my company's MacBook Pro 9.1 (mid 2012).

USB 3 is extremely slow.

I usually connect SSD via USB-to-SATA adapter. I also have SSD inside the macbook.

If I perform plain old dd-copy (dd if=/dev/diskX of=disk_image.raw) I get ~23 MB/s transfer speed. I've tried several USB3 drives and it gave me the same terribly slow speed.

Dear Apple, please make an effort to solve this problem.

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Answer 7

mzew

Level 1

0 points

Aug 7, 2015 3:23 AM in response to dominic23

This is not an explanation. Leave this magic for windows world.

UPDATE: I've booted my MacBook Pro 9.1 with Linux and tested USB speed again with the same drives. It gave me ~106 MB/s.

This proves, that USB problem lies in Apple's USB drivers.

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Answer 8

Ve3tro

Level 1

0 points

Aug 10, 2015 3:51 PM in response to mzew

What happens if you eject the drive in OSX pull the USB 3.0 cable out then replug in?

For me when booting up it registers my USB 3.0 HDD at USB 2.0 speeds but if I eject then replug back in the speeds will go up to USB 3.0.

I checked System Information and in the USB panel it would say my HDD is registered to the High-Speed bus but if I unplug then re-insert it becomes Super-Speed bus. Its an annoying bug that Apple never seem to acknowledge and probably has something to do with the OS starting up and USB 3.0 connections.

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