Need to recover SSD partition table using Gdisk on Samsung 512GB on MBP MID 2015

BackBay wrote:

HWTech has some good recommendations but my Question is: Is there a way to do the (dd) or the better GNU (dd) using a disk image so I can send it to the sandisk I booteded from? (I'm pretty sure I saw this in one of the manuals)

Yes you can send the information into a raw image file by specifying the destination path as a file (replace "diskN" with the drive identifier for the bad SSD):

sudo  ddrescue  --ask  -n  /dev/diskN   ~/Desktop/samsung-clone.img   ~/Desktop/mapping-file.txt

Alternatively, if I install the new apple drive aura pro 480gb: First, the Samsung will not show up (not kidding)

Very odd, but I've seen a lot of odd behaviors with recent Macs. This may be telling us something, but I'm not sure what yet.

Second, it may be cutting it close as far as needing the same amount of space for the data needed for cloning as I am not sure how much was full on the 512GB Samsung drive.]

I'm a bit concerned that your bad Samsung drive is a 512GB drive, but gdisk is only reporting it as 250GB. I just thought the tile of this thread was mistyped.

What I do have is two thunderbolt ports (no proprietary cord for that) another 1TB Sandisk SSD I can empty if needed. and an HDMI port but none of that helps this situation I think.

FYI, if you have any other non-Apple computer with more ports, then you can use that system to clone the bad SSD using a Linux boot disk such as Knoppix which already includes GNU ddrescue. A bit for bit clone is the same regardless of what system does the cloning process.

Or you can purchase a powered USB3 hub to connect multiple USB drives to this Mac. While it is possible to actually attempt the repairs using the raw image file itself macOS tools/utilities don't always work well with them. In the end I find it easier to just push the clone to a spare drive to work from a real drive.

HWTech wrote:

There is a simple to use command "gpt" which can restore the partition table using the backup copy:

sudo gpt recover diskN

If the backup table was available, GDisk should have read it. OP sees this.

Warning! Read error 16; strange behavior now likely!
Warning! Read error 16; strange behavior now likely!

See Semi-Automated Recovery section in https://www.rodsbooks.com/gdisk/repairing.html. If both primary and backup tables are corrupted during power failure, there is a much larger issue with the laptop/SSD controller firmware.

Post the output of

sudo gdisk -l /dev/disk2

If you get a permission error, temporarily disable SIP. What is the brand/model of the internal SSD?

Since you have 2015 Mac, assuming it is the first 4K disk device, I recommend using

sudo gpt -vv -r show /dev/disk0
Password:
gpt show: /dev/disk0: mediasize=1000555581440; sectorsize=4096; blocks=244276265
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: Sec GPT at sector 244276264
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2          4         Pri GPT table
          6      76800      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
      76806  150390778      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
  150467584   93808640      3  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  244276224         36         
  244276260          4         Sec GPT table
  244276264          1         Sec GPT header

A dd command is also available on macOS, since you are booted from an external disk. It can be used to make a copy, but will need the same disk space as the size of the SSD for this to work correctly. It should be done first, before GDisk manipulates this disk in any way.

GDisk will create the backup GPT table, once you do the write. The Pri and Sec entries will be cerated. You can also create the EFI.

If you run

sudo dd id=/dev/rdisk0 count=5 2>/dev/null | hexdump -C

what do you get? This will give us the first 5 'sectors' of the on-disk structure.

I'm not use to using gdisk so thanks for the information.

I agree the SSD has most likely become corrupt from the power failure. SSDs are very susceptible to power issues which is why I strongly cautioned the OP to contact a professional data recovery service.

Hey,

I think I had similar problem (still have it). Out of nowhere my macbook pro late 2013 shut down and when I tried to turn it on I had blinking folder. It wasn't recognized by the computer and I needed to save my files. I tried number of things, but unfortunately non of them worked. I went to professional at the very end knowing that that will cost me 600 euros. And they told me that there is a firmware problem and that they cannot fix it at the time, because there is no existing program that can run a repair for that advanced ssd (even though it is 7 year old, at least). As they explained there was a problem with ssd self repair part of the disk (or something like that). Also Samsung original ssd factory installed.

If you find and answer to your problem, please share.

All the best.

The two layouts are shown

sudo gpt -vv -r show /dev/disk0
Password:
gpt show: /dev/disk0: mediasize=1000555581440; sectorsize=4096; blocks=244276265
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: Sec GPT at sector 244276264
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2          4         Pri GPT table
          6      76800      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
      76806  150390778      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
  150467584   93808640      3  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  244276224         36         
  244276260          4         Sec GPT table
  244276264          1         Sec GPT header

and...

sudo gpt -vv -r show /dev/disk0
Password:
gpt show: /dev/disk0: mediasize=512110190592; sectorsize=512; blocks=1000215216
gpt show: /dev/disk0: PMBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: Sec GPT at sector 1000215215
       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34           6         
          40      409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
      409640   999543392      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
   999953032      262144      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  1000215176           7         
  1000215183          32         Sec GPT table
  1000215215           1         Sec GPT header