I’ve got 2 Thunderbolt Duo drives ( 2 x 2TB =4TB configuration).
Functioning as external drives for :-
Model Name: MacBook Pro
Model Identifier: MacBookPro11,5
Processor Name: Intel Core i7
Processor Speed: 2.5 GHz
Memory: 16 GB
Boot ROM Version: MBP114.0172.B07
SMC Version (system): 2.30f2
mac OS 10.11.2
One of the drives has developed a fault.
Here’s the background.
They were configured in a raid 1 set under mac OS via terminal commands.
Drive A on enclosure 1 … mirrored on Drive A enclosure 2
Drive B on enclosure 1…. mirrored on Drive B enclosure 2
I used terminal commands to create the raid sets (not WD utilities)
Drive A had 3 partition and drive B had 2 partitions ( both drives were partitioned identically to
By the way this worked fine but data transfer was very slow ( about 65 MB/s read and write
speeds according to BlackMagic disk speed test)
Anyway I decided to break the raid sets to see if this improved speed (which it did a little …up to
about 87 MB/s).
However after breaking the raids back into seperate volumes one of the physical disks wasn’t
showing up in finder or Disk Utility.
So I ran the following terminal command :-
system_profiler SPSerialATADataType -detailLevel medium
This revealed that all the disks were recognised by the OS ( I confirmed their physical serial
numbers and they were all reported as “mounted” but I noticed that two of the disks had identical
UUIDs. …and this seemed to be confusing the OS into seeing both of them but only showing 1 of
them in finder.
So next I erased 1 drive with the conflicting UUID, because, apparently doing so assigns a new
That worked fine the disk was visible in finder
But now the other drive that had the same UUID won’t show up at all and doesn’t even spin up…
nor will any other drive put into that slot. The drive itself is fine I’ve checked it in other enclosures.
It’s as if that physical slot has been disrupted somehow in firmware.
Alternately it’s just a coincidence and it’s just some sort of hardware failure that has nothing to do
what I’ve outlined above.
The bottom line is that drives won’t spin up in slot A of one of my Thunderbolt Duo enclosures
and any suggestions or insights would be appreciated.