So I have an external HDD, I believe it's a Hitachi, 2tb, working fine EXCEPT: when I formatted this, it was via e-SATA, thru an Expresscard slot in my Mac Book Pro A1151, 2 partition, NTFS/Fat32. The enclosure I'm using is a Sabrent, e-sata/USB - solid.

It recognizes in SATA connection but not in USB - every time I connect via USB (in either OS X or Windows) it sees the drive but no file system/files and wants to be formatted.


  • From your description and troubleshooting, sounds pretty much like bad hardware... Enclosure, USB cable, USB port, or possibly power (if USB powered). – acejavelin Feb 3 '16 at 0:18
  • hm - I suppose I never considered that. thanks for the insight, I guess the only solution is to remove it from the enclosure and test it via a dock or swiss army hook-up. – Jujube Feb 3 '16 at 0:25
  • If it always works via eSATA, you can pretty much say the drive itself is OK... My money is on the enclosure or cable. Are you trying to connect both eSATA and USB simultaneously? That would fail in most enclosures, some older ones required a power cycle between changing interfaces. – acejavelin Feb 3 '16 at 0:34
  • Maybe because of this. USB is trying to be smart while eSATA just relays data without any translation. – Kamil Maciorowski Dec 17 '18 at 9:08

It sounds to me, you have a very similar problem, what I have. My case is exactly reverse of yours :-) Your hardware is ok. Can you try to mount the disk and run fdisk under Linux (and post the output) ? In my case the problem was, Windows doesn't create an MBR-type partition table; it just creates a single large partition, and allocates the whole space of the harddisk for it. Maybe this is the problem in your case too.

USB sticks behave in this way under Windows. If you format a stick (even if it's 128GB or bigger), the entire space is allocated for one partition, wihtout creating the MBR.

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