I bought two 2TB 2.5" external HDDs that came with the following warning message in a Readme file contained in the drives.

"The drive can only be formatted with Exfat and cannot be formatted in other for mats, suchas NTFS, FAT32, FAT. Otherwise it will cause the hard drive t be unusable! This hard disk is only suitable for windows system and XP system not suitable for PS4, xbox macbook,tv, etc. The disk needs to be inserted into the USB interface of the device's motherboard. If the transfer method is used, there may be insufficient power supply to the disk."

Both drives appeared to work straight out of the box. However, I got errors when trying to partition them (I use a MBP, mid-2015 Retina, MacOS 10.3.3). Now one of the external drives has become unusable. So...I'm guessing this could be because these are cheap no-brand drives which I ordered from China, similar to these:

And I'm guessing the manufacturer has assembled them or configured them in this way (limited to Exfat) in order to cut costs. My questions are:

  1. Why/how an external drive can be manufactured to be permanently only Exfat?
  2. Is this a hardware constraint or physical limitation imposed by the manufacturer or by the USB to SATA bridge used?
  3. Is there a way to overcome this so that I can use them for Time Machine backups?...Has anyone been succesful in backing up with Time Machine on these types of 2.5" external hard drives?

Attempts at finding answers:

My investigation so far has brought me to this: https://apple.stackexchange.com/a/150702/182479 (which hints that it could be related to the controller of the external case)

From the Terminal query below, it appears that the drive is a JMicron device. I've now got in touch with JMicron and waiting to hear back (will post updates here). In the meantime, if anyone can shed any light and answer/respond to any of the above questions I'd very much appreciate it.

diskutil info /dev/disk1:

   Device Identifier:        disk1
   Device Node:              /dev/disk1
   Part of Whole:            disk1
   Device / Media Name:      JMicron Generic Media

   Volume Name:              Not applicable (no file system)

   Mounted:                  Not applicable (no file system)

   File System:              None

   Content (IOContent):      FDisk_partition_scheme
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 USB
   SMART Status:             Not Supported

   Total Size:               2.0 TB (2000398934016 Bytes) (exactly 3907029168 512-Byte-Units)
   Volume Free Space:        Not applicable (no file system)
   Device Block Size:        512 Bytes

   Read-Only Media:          No
   Read-Only Volume:         Not applicable (no file system)
   Ejectable:                Yes

   Whole:                    Yes
   Internal:                 No
   OS 9 Drivers:             No
   Low Level Format:         Not supported

Below is a screenshot showing the readme file and the warning contained in it.

enter image description here

NB. Question asked earlier to try and restore the unusable drive here Unusable 2.5" external HDD. Partition failed with the error -69760: Unable to write to the last block of the device. Exfat only? Repairable?).

  • I think all the errors in the readme file says it all. Bite the bullet, eat the loss, and get some quality hardware. Especially if you're using it for backups! May 22, 2020 at 15:51
  • Had I read this file in an online description before buying I would've thought twice about ordering. Having said that, I'm curious to learn more about these type of disks. May 22, 2020 at 15:55
  • It depends on which of those 3 you bought from & if you are actually UK. 1st ad, US, don't know. 2nd ad, send back as "unfit for purpose" Look up UK "distance selling regulations" They pay postege, both ways, you get total refund. 3rd ad, you were warned. You can still return within 14 days of receipt, but YOU pay return postage. [Look up those regs & make sure you KNOW them in future]. Sellers will try to blame you.
    – Tetsujin
    May 22, 2020 at 16:07
  • @Tetsujin it was the second one which is now unlisted. I posted the other ones as examples (third one by searching the readme in Google). Yes I'll most probably return (I think for eBay, shouldn't need to pay return postage if mis-sold). I was posting this questions because I'm genuinly curious about these types of drives and if it was a software/hardware constraint. May 22, 2020 at 16:11
  • 1
    Thank you for trying to help Tetsujin! I always seem to find you and @Klanomath around in SE. I'm keeping this question open so I can update it if I hear back from JMicron or from anyone else who can shed some light. So far it seems these Chinese manufacturers have been able to make and sell a very cheap yet large external hard disk with the exception that it only works with Exfat. It's like they've created a new product. That's partly why I'm curious to know more. May 22, 2020 at 16:44


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