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Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
Hi all,
I have an Apple USB-c to USB adapter.
I have an M2 SSD in a micro USB case.

Up until today, I was getting around 330mb write and 400mb read speeds on it using BlackMagic Disk Bench tool.

Now I am getting under 5mb!

When i plug it into my old 2012 rMBP I get around 330mb write and 400mb read speed.

When I plug another USB3 HDD into the rMB, using the USB-C -USB adapter and same USB cable, I get 65mb/s write and 80mb/s read (which is normal for that drive)

I have tried erasing an repartitioning etc, but to no avail - same shocking performance.
I have reset PRAM & SMC. Made no difference.

Any ideas?
 
Last edited:

Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
UPDATE:

I've tried the USB SSD on another rMB, same issue it gets detected, but you cannot use it. I can see it but i can't format/partition it or copy files to it.

I've tried another USB-C adapter, made no difference.
I've tried a fresh install of just the OS, no difference.

The USB SSD works 100% fine on anything I try it on.

I don't understand how it worked for the last few weeks, and now it doesn't - but it works on everything else.
 

Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
bit the bullet, and pulled out the Transcend 480GB SSD from the 2012 rMBP and put it into the USB enclosure.

Tried it on the rMB using the USB-C to USB adapter, I get 400mb/s read, 450mb/s write.

So its not the enclosure.

in summary;

Transcend USB enclosure + Transcend SDD + rMB = works perfectly
Transcend USB enclosure + Apple SDD + any other machine = works perfectly
Transcend USB enclosure + Apple SDD + rMB = no good - unusable.


Weird!
 

dudup

macrumors regular
May 28, 2008
173
0
Lisbon, Portugal
I'm having the exact same problem with my Transcend Jet Drive SSD enclosure and an 2012 15" rMBP 256 GB internal SSD. It works great and has rock solid speeds on any other Mac or PC. It just won't work correctly with the rMB and its USB-C to USB adapter.

I've ordered a USB-C x USB 3.0 Micro B cable to check if it's an issue with Apple's adapter or with the case (http://www.amazon.com/Cable-Matters...Q710/ref=sr_1_8?ie=UTF8&qid=1441650755&sr=8-8). Will post the results in the next few days.
 

dudup

macrumors regular
May 28, 2008
173
0
Lisbon, Portugal
Received the cable but no difference at all, the erratic and slow behavior still goes on.

So it seems to me that some USB 3.0 drives are not compatible with USB-C.

Will keep looking for a solution.
 

Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
Received the cable but no difference at all, the erratic and slow behavior still goes on.

So it seems to me that some USB 3.0 drives are not compatible with USB-C.

Will keep looking for a solution.

I've tried different cables and different USB-C to USB adapters too, no difference. I've just logged a support call with Transcend - will update you with any info i get back from them.

Wonder if the OCW Envoy Pro would work any better.
http://eshop.macsales.com/shop/SSD/OWC/Air-Retina/Apple-MacBook-Pro-Retina-2012-Drive-Internal-Flash
 

SteveJUAE

macrumors 601
Aug 14, 2015
4,476
4,725
Land of Smiles
UPDATE:

I've tried the USB SSD on another rMB, same issue it gets detected, but you cannot use it. I can see it but i can't format/partition it or copy files to it.

I've tried another USB-C adapter, made no difference.
I've tried a fresh install of just the OS, no difference.

The USB SSD works 100% fine on anything I try it on.

I don't understand how it worked for the last few weeks, and now it doesn't - but it works on everything else.

I can't say I had the exact same experience as you but I did notice when using a thumbdrive to install bootcamp some would work and others did not, but had previously been ok on my old rMBA's
 

dudup

macrumors regular
May 28, 2008
173
0
Lisbon, Portugal
I've tried different cables and different USB-C to USB adapters too, no difference. I've just logged a support call with Transcend - will update you with any info i get back from them.

Wonder if the OCW Envoy Pro would work any better.
http://eshop.macsales.com/shop/SSD/OWC/Air-Retina/Apple-MacBook-Pro-Retina-2012-Drive-Internal-Flash

It's very likely it uses the same chipset, and I believe the chipset is the one to blame.

I'll try to open another an issue on Transcend support as well, it should help if more people report it. Even though this is an edge case, it'll probably grow as USB-C makes its way to other Macs.
 

Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
It's very likely it uses the same chipset, and I believe the chipset is the one to blame.

I'll try to open another an issue on Transcend support as well, it should help if more people report it. Even though this is an edge case, it'll probably grow as USB-C makes its way to other Macs.

Bummer!!!! Just got this back from Transcend;

Dear Transcend Customer,

Thank you for contacting us.

Transcend JDM and the enclosure are incompatible with the new macbook.
The interface of JDM is SATA and the interface of the new macbook is PCIE, JDM and the enclosure cannot be used with new macbook.
________________

My Western Digital and Seagate non SSD work fine. I've just tried a desktop SSD (Sandisk 240GB Plus) in a 2.5" USB to SATA case - it doesn't work either!

So what SSD USB drives can I use? I guess only PCIE ones.

Anyone got a suggestion of what drive?
 

Mattymoocow

macrumors member
Original poster
Jun 27, 2010
95
23
Bummer!!!! Just got this back from Transcend;

Dear Transcend Customer,

Thank you for contacting us.

Transcend JDM and the enclosure are incompatible with the new macbook.
The interface of JDM is SATA and the interface of the new macbook is PCIE, JDM and the enclosure cannot be used with new macbook.
________________

My Western Digital and Seagate non SSD work fine. I've just tried a desktop SSD (Sandisk 240GB Plus) in a 2.5" USB to SATA case - it doesn't work either!

So what SSD USB drives can I use? I guess only PCIE ones.

Anyone got a suggestion of what drive?

Update - I purchased a Samsung Portable T1 SSD USB drive.

It works and runs at high speed.

It does have it own set of limitations though.
 
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