Weird Problems with Seagate USB 3.0 5TB Hard Drives and Mac OS X

I’ve been having an odd issue with my Seagate drives and I’ve run out of troubleshooting ideas. I have a 2011 iMac (OS X 10.9) which only has a USB 2.0 ports. However, I have a CalDigit Thunderbolt dock which gives me USB 3.0 capability and very fast USB 3.0 transfer speeds for most of my external disks.

Summary of my problem:
I cannot write to my Seagate 5TB USB 3.0 drives using the USB 3.0 connection on either of my Macs. If I do the file copy stops at 1%, the Finder freezes and I can’t even reboot. However, I can read files fine over USB 3.0. Just not write.

They work fine on my Mac using USB 2.0, I can read and write fine. On my Windows 8.1 PC, the USB 3.0 write and read is fine (if I format the disk to NTFS). The disks are formatted using GUID and Mac OS Ext. (Journaled).


I have a series of Western Digital and other USB 3.0 hard drives which operate at USB 3.0 speeds. I can read and write to and from across these disks, and my iMac’s internal disks, with no problem.

However, I also have four Seagate 5TB USB 3.0 Expansion drives. I purchased these while on sale a while back for the sole purpose of using one as a photo drive and one as a video drive, each with a spare drive to use as a cloned backup. So 2 active drives and 2 backup drives.

Somewhere along the line something stopped working. Maybe it was after I upgraded to OS X 10.9, or after a minor Software Update. Either way, I can no longer correctly write to the Seagate 5TB drives if using a USB 3.0 port. Previously this was not a problem, as my photo drive has over 3TB of data on it currently.

The Seagate 5TB drive is seen by my Mac, I can copy files from the drive quickly, but if I try and copy files to the drive after the copy starts everything freezes and the Finder becomes unresponsive. I can’t cancel the Copy dialog box, it just says “Stopping” and hangs. I can’t even perform a restart, if I do the Mac hangs at a gray screen after trying to log off. Killing the Finder or Force Quitting doesn’t help either. Instead, I must hold down the power button until the Mac turns off.

Now, I thought okay maybe it’s just a bad drive? But all four of them being bad, purchased from two different sources? I doubt it.

So I decided to run some tests with a 1.24 GB .zip file containing photos with my computers. This same file was used across these tests. Note the different results depending on the OS and the USB port used.

Tests using the USB 3.0 port on the computer
Computer OS Seagate 5TB Drive Formatted As Write Results Read Results
2011 iMac OSX 10.9 GUID – Mac OS Ext. (Journaled) Failed* OK
2008 MacBook Pro OSX 10.10 GUID – Mac OS Ext. (Journaled) Failed* OK
Intel i5 Skylake PC Windows 8.1 GUID – NTFS OK OK
2011 iMac OSX 10.9 GUID – NTFS Failed** OK
*Copy window starts at 1%, then the Finder freezes. Can’t cancel the copy. A hard reboot is required, you can’t restart normally.
**Using Seagate’s Paragon NTFS for Mac OS X driver which allows Mac OS X to write to Seagate NTFS hard drives


Tests using the USB 2.0 port on the computer
Computer OS Seagate 5TB Drive Formatted As Write Results Read Results
2011 iMac OSX 10.9 GUID – Mac OS Ext. (Journaled) OK OK
2008 MacBook Pro OSX 10.10 GUID – Mac OS Ext. (Journaled) OK OK
Intel i5 Skylake PC Windows 8.1 GUID – NTFS OK OK
2011 iMac OSX 10.9 GUID – NTFS** OK OK

Note that this problem does not occur if I use the iMac’s built in USB 2.0 port, but of course at reduced USB 2.0 speed. I can’t even format the drive in Disk Utility on my Mac using a USB 3.0 connection, it just hangs after 50% of the way complete.

I do not get this problem on my Windows 8 PC with USB 3.0 ports. If I take a Seagate drive, plug it into Windows and format it as NTFS, I can read and write normally without a problem on Windows 8. But what about my Mac? Well I even tried using the Seagate NTFS driver which (which allows Macs to write to an NTFS drive). Still, I get the same issue. Hanging copy window, can’t even stop it.

Now, one may assume it’s an incompatibility with OS X or the CalDigit Thunderbolt Station I’m using. However, my 2008 MacBook Pro (OS X 10.10) has an ExpressCard slot with a USB 3.0 adapter. I have the same exact issue on my MacBook Pro as I do with my iMac. Sadly, I don’t have any recent Macs with USB 3.0 built-in to test this on. However, my assumption is that there must be something wrong with the USB 3.0 chipset in these Seagate drives, or the formatting – which doesn’t like my iMac… or something!

I have no problems using my Toshiba and Western Digital USB 3.0 drives. They work fine, and at full USB 3.0 speed. The only incompatibility I’ve ever had with my CalDigit Thunderbolt Station USB port was while using a Sabrent brand (USB-DSC8) SATA to USB 3.0 adapter. That simply didn’t work on a USB 3.0 port (didn’t even show up under Apple System Profiler), but worked on the built-in USB 2.0 port. However in this case, the Seagate drives show up and appear to work fine… unless you try to write to them.

The models of the Seagate 5TB USB 3.0 external hard drives I have are:

  • Two Seagate “Expansion Desktop Drives”, Model: SRD0NF2, Part Number: 1TFAP3-500 5 TB
  • Two Seagate “Expansion +”, Model: SRD0NF2, Part Number: 1V9AP5-5oo 5 TB

Does anyone currently own a Seagate USB 3.0 external hard drives and have a Mac with a USB 3.0 port?

If so I’d be greatly interested in hearing if you are experiencing any issues. 🙂

With thanks,