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Level 1

47 points

Target disk mode very slow in one direction

Hi there,

I'm having a problem when using target disk mode and that is has suddenly become very slow in one direction.

I have a 2015 Mac Pro and 2015 Mac Book Pro. Prior to experiencing this issue, I could transfer extremely fast via target disk mode, no matter which of the machines was set the 'target disk mode'.

Tonight I've found that if I set the Mac Book Pro to 'target disk mode' and try copying 170gb, it says it will take approx 11 hours. If I do the reverse and set the Mac Pro into 'target disk mode' then I am able to copy the 170Gb in about 8 minutes which is what I was used to (when in the past I'd set the Mac Book pro to 'target disk mode').

I really need to be able to get the speed back for so that I can use the Mac Book Pro in 'target disk mode' again.

I've tried restarting both machines, tried a different thunderbolt cable, ran disk utility on both disks not finding any errors, tried plugging to different thunderbolt ports, removing other devices...

If anyone has some suggestions that would be much appreciated.

Ross

Mac Pro, OS X El Capitan (10.11.6)

Posted on Dec 14, 2016 4:42 AM

Best reply

GNXClone

Level 1

4 points

Posted on Jan 5, 2017 1:45 PM

This is purely a guess, but I think when the MBP boots into target disk mode, it's not actually running Sierra.

Therefore, I think Sierra updated the firmware and broke TDM over TB.

For my MBP, the latest firmware version I can find a reference to online is: MBP112.0138.B16

But my MBP is showing: MBP112.0138.B18

I tried rolling the FW back to MBP112.0138.B16 using:

sudo /usr/sbin/bless -mount / -firmware ~/Downloads/MBP112_0138_B16_LOCKED.scap --verbose

But it returns with an error:

Could not set boot properties: 0xe00002bc

Error while writing firmware updater for EFI

The Thunderbolt driver is version: 17.1

I did some Blackmagicdesign tests as well.

MBP (Retina, 15-inch, Mid 2014) with Sierra in TDM connected to an iMac: Write 8.6MB/s, Read 7.2MB/s

MBP with Sierra using IP over TB to iMac: Write 89.6 MB/s, Read 20.1 MB/s

A different MPB, same specs but with El Capitan in TDM connected to iMac: Write 668.7 MB/s, Read 448.6 MB/s

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21 replies

Jan 7, 2017 3:38 PM in response to Ross Lindsay

Thanks Ross.

Based on what GNXClone found it does look like this new firmware was released in December. It may have also been included along side the latest update for El Capitan.

tessive

Level 1

4 points

Jan 10, 2017 1:40 PM in response to GNXClone

Excellent test! I'm seeing the same low throughput on my Macbook Pro Retina 15 with Sierra in target disk mode. Seems like something is broken. I submitted a bug to Apple.

Jan 17, 2017 3:09 PM in response to Ross Lindsay

This is now being addressed with Apple Enterprise Support. I'll update you as they update me.

Ross Lindsay Author

Level 1

47 points

Jan 17, 2017 3:15 PM in response to cosmicpictures

Much appreciated. Thanks.

Jan 25, 2017 11:12 AM in response to Ross Lindsay

I can also confirm a drastic improvement.

tessive

Level 1

4 points

Jan 29, 2017 8:13 AM in response to cosmicpictures

Just tested 10.12.3, and the problem seems to be gone now. Back to full speed.

Target disk mode very slow in one direction