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I have an external HDD Toshiba MQ01ABD100 1TB HDD in an external enclosure. Recently it suddenly no longer accessible. When plugged to a Mac, it will prompt "The disk you inserted was not readable by this computer" with 3 option: Intialize..., Ignore & Eject. I would like to recover the data on this external HDD as I've copied some work files there as backup before I redo my Macbook. I'm using the iMac at work to post this & would be doing the recovery work here too.

Here are the results of some of the commands I saw ran in other topics...

diskutil list

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            999.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

/dev/disk1 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *1.0 TB     disk1
   1:               Windows_NTFS                         1.0 TB     disk1s1

diskutil info disk1

Device Identifier:        disk1
   Device Node:              /dev/disk1
   Whole:                    Yes
   Part of Whole:            disk1
   Device / Media Name:      MQ01ABD100

   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

   Disk Size:                1.0 TB (1000204886016 Bytes) (exactly 1953525168 512-Byte-Units)
   Device Block Size:        512 Bytes

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

   Device Location:          External
   Removable Media:          Fixed

   Virtual:                  No

sudo fdisk /dev/disk1

Disk: /dev/disk1    geometry: 121601/255/63 [1953525168 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: 07 1023 254  63 - 1023 254  63 [         2 - 1953525166] HPFS/QNX/AUX
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused      

Added: 21/APR/2019

sudo gdisk /dev/disk1

GPT fdisk (gdisk) version 1.0.4

Partition table scan:
  MBR: MBR only
  BSD: not present
  APM: not present
  GPT: not present


***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory. THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by
typing 'q' if you don't want to convert your MBR partitions
to GPT format!
***************************************************************

Warning! Main partition table overlaps the first partition by 32 blocks!
You will need to delete this partition or resize it in another utility.

Warning! Secondary partition table overlaps the last partition by
33 blocks!
You will need to delete this partition or resize it in another utility.

ADDED: 23/APR/2019

RESULT of sudo dd if=/dev/disk1 skip=1 count=2 2>/dev/null | hexdump -Cv

00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000120  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000140  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000150  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000170  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000200  eb 76 90 45 58 46 41 54  20 20 20 00 00 00 00 00  |.v.EXFAT   .....|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000220  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000230  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000240  02 00 00 00 00 00 00 00  ae 6d 70 74 00 00 00 00  |.........mpt....|
00000250  00 08 00 00 00 f0 00 00  00 f8 00 00 75 6f 74 00  |............uot.|
00000260  0b 00 00 00 bf 56 15 58  00 01 04 00 09 08 01 80  |.....V.X........|
00000270  34 00 00 00 00 00 00 00  f4 f4 f4 f4 f4 f4 f4 f4  |4...............|
00000280  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000290  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002a0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002b0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002c0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002d0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002e0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000002f0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000300  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000310  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000320  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000330  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000340  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000350  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000360  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000370  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000380  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
00000390  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003a0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003b0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003c0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003d0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003e0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 f4 f4  |................|
000003f0  f4 f4 f4 f4 f4 f4 f4 f4  f4 f4 f4 f4 f4 f4 55 aa  |..............U.|
00000400

I've tried reading other posts that came up googling using the error messages and it seems to point to corruption of the partition table ? Hope someone could advice & guide me through this process. It's super frustrating as I can't seemed to be able to fid anything that's similar to this.

Regards, chris

  • What did you expect to find. How many volumes? What types of volumes? There is APFS, JHFS+, NTFS, FAT, ExFAT, etc. Do you know if the drive was using a MBR or GPT type partitioning? – David Anderson Apr 20 at 19:09
  • @ David Anderson - There's only 1 volume on this ext hdd. It's formatted using Disk Utility. The volume type is ExFAT and using MBR type partitioning. – Chris Quek Apr 21 at 2:50
  • BTW, "You will need to delete this partition or resize it in another utility."... what utility ? – Chris Quek Apr 21 at 10:39
  • @David Anderson any ideas ? – Chris Quek Apr 23 at 3:38
  • The value of 2 in the start column of the fdisk output looks suspicious. You could post the output from dd if=/dev/disk1 skip=1 count=2 2>/dev/null | hexdump -Cv. You might have to do a diskutil unmountdisk /dev/disk1 before entering the command. – David Anderson Apr 23 at 4:00
1

Before doing any more scans and operations on the device, it is worth connecting the drive to a different device. Mac/Windows just see if it works. It could be that the physical drive may be damaged or shocks could've damaged or corrupted the controller/data.

The fact that it is only recently that it has suddenly changed state would indicate that there may be a problem with the hardware. It is possible, so get it checked just to be sure.

Is the cable you are using USB Micro-B? Check to make sure it isn't bent or damaged. It is unlikely that it would cause this type of fault, but just check to make sure.

I would suggest doing these checks before changing the partition scheme, as that can cause loss of data by erasing and corruption.

  • I've done all that and verified it doesn't work before coming here. Thanks. – Chris Quek Apr 23 at 3:33
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Besides trying with another computer and OS, as mentioned before, a disk repair program might be able to help here. If your files are important, you should first make a copy of the disk by copying a block-by-block image of it to another disk. Then you can experiment with different repair options or, if all fails, try to extract the most important documents manually (Only useful to extract some of the text and copy it into new documents).

On a side not, FAT, ExFAT and such have no journaling, and accordingly not a lot of options to repair them if something goes wrong - like a power outage during a write operation. They also don't preserve all the headers - like camera information for your pictures. It's generally better to use a more modern format like APFS or NTFS. You should use such older formats only for temporary uses like data transfer, never for backups of important data.

  • 1
    thanks for suggestion. I'll do that if all else fails. – Chris Quek Apr 23 at 3:34
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This is just to notify everyone that after many days of waiting, I have decided enough of waiting, time for next plan. I had hope that someone would be kind enough to guide me through the steps required to fix the corrupted MBR (that that's the case) and maybe I won't have to go through the tedious steps of doing a full disk scan using tools like TestDisk or PhotoRec. It seems like that is not to be.

I have now completed a full disk scan using PhotoRec tool, ran some scripts i found on the internet to sort the files according to filename extension. For the photo files, I am in the process of renaming the files according to date created.

Thank you to those who have answered. I am aware & fully understand that any assistance provided is purely on voluntary basis. So while I am disappointed with how this turns out, I fully understand. Consider this closure of this thread.

Have a good day.

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