I had one of these "Seagate Backup Plus 4TB Desktop External Hard Drive USB 3.0" Maybe it was 3TB version(HDD is showing ST4000DM) and the enclosure connector got broken and I disassembled the enclosure and took out HDD and directly connected to PC with USB to SATA connector. But when it is connected to PC it is showing as not partitioned and I can't find my files. Question: Could it be that the enclosure uses different type of partitioning or way to read the files? Reason why I am asking is that I don't recall doing anything that updates partitions or writes to this enclosure. What would be the best way of restoring files from this situation? Thanks.
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Ufortunately, these drives often need the original controller because of badly implemented encryption algorithms. A) You might be entitled to Seagates Rescue Data Recovery– 1NNCommented Jan 26, 2022 at 14:16
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B) otherwise, broken USB connectors can be soldered. Ask for help at your local hardware repair store.– 1NNCommented Jan 26, 2022 at 14:21
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1NN, a encrypted drive needs decryption when being read out. Even the use of a "well implemented" encryption algorithm requires decryption upon read transaction. Therefore the quality of implementation does not play a role. Manufacturers won't waste money putting encryption on a additional interface when encryption can be handled by the drive firmware as this is already the case.– r2d3Commented Jan 26, 2022 at 19:01
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2 Answers
Both versions of your drive (3TB, 4TB) won't run with legacy operating systems that don't support the modern GPT partition table instead of the old MBR style one. Old legacy systems are typically limited to a maximum drive size of 2TB.
Your internal drive probably has a native sector size of 4096 byte but is showing a logical size of 512 bytes at the interface.
When reversing that translation by using an additional board legacy operating systems can use the drive to its full extend.
Using the drive without the additional interface will lead to your operating system searching your partitions at the wrong location. I am not sure if fixing the partition table would be sufficient to heel the problem. Therefore I recommend buying an expensive hard disk drive with a logical sector size of 4096 bytes at the interface. Once you duplicate your drive sector-wise onto the new drive the partition should become visible again.
The preferred mean of duplication is dddrescue which can be run off a live linux edition like Knoppix and I think it is contained in the small CD-rom-size editions of Gparted and SystemRescueCD as well.
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Thanks. I wish I could give you +. How to duplicate sector by sector? What tool to use?– dagnaCommented Jan 26, 2022 at 23:19
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:) I added the response to your question to my answer. Good luck!– r2d3Commented Jan 27, 2022 at 0:10
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While cloning to an AF 4Kn drive will "fix" the problem, the rationale in this answer is quite the opposite to the fact. Also rather than "sector-wise", it's more of "byte-wise" / "bit-wise", since you don't want the tool that clone for you to pad the the data from the source in any way but simply fill each block on the destination drive with data of eight blocks on the source.– Tom YanCommented Jan 27, 2022 at 7:04
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Thanks. I think while I am waiting for my drive to arrive, I should try to fix the partition table. what tool should I use? Since I will work only with a couple of sectors then I think I could back up the sectors before updating them manually to restore them if the attempt fails.– dagnaCommented Jan 28, 2022 at 14:39
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When I tried some file recovering programs it could find the Picture files from HDD. I am guessing If I have to do is update the partition table then it should be fine.– dagnaCommented Jan 28, 2022 at 14:47
AFAICT, the drive is NOT an AF 4Kn drive but has logical block size of 512, and it has MBR partition table instead of GPT.
The original enclosure has a mapping layer that makes it appear as a AF 4Kn drive (i.e. having the logical block size of 4096 bytes) by "grouping" eight 512-byte logical block as one 4096-byte logical block, which allows MBR partition table to be used on drive larger than ~2TiB.
The limitation is due to the maximum number of blocks can be represented with 32-bit unsigned integer (i.e. 0xffffffff). When the block size is 4096-byte, that value is equal to ~16TiB instead of ~2TiB.
Here's the math of how the partition that was created with logical block size of 4096-byte appears as what you see now:
>>> 3726 * 1024 * 1024 * 1024 / 4096
976748544.0
>>> 976748544 * 512 / 1024 / 1024 / 1024
465.75
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The drive IS an Advanced Format Drive because it uses a physical sector size of 4096, checked with some secondary class sources. "ST4000DM" is the prefix for a family of drives which all use this sector size. The question of using a translation like 512e does not matter when qualifying this drive as being "Advanced Format". Advanced Format is a term that describes drive internals regardless of sector emulation at the interface. See: seagate.com/tech-insights/…– r2d3Commented Jan 28, 2022 at 12:03
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@Tom Yan. Does it mean that If manually update the partition table then I should be able to see the files?– dagnaCommented Jan 28, 2022 at 14:34
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@r2d3 I specially stated that it is NOT AF 4Kn but has logical block size of 512 (i.e. it can be 512e or just "512/512"). Physical block size is NOT relevant to the issue in the OP at all.– Tom YanCommented Jan 28, 2022 at 19:34
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@dagna No, as I mentioned in the other comment, cloning to a drive with logical block size of 4096-byte (as suggested by @r2d3) IS the solution. It just that you need to make sure the cloning tool does not perform the cloning in some LBA to LBA manner (i.e. each 512 block is padded to the size of 4096 with zeroes or so). The default behavior of
dd(not sure aboutddrescuewhich is not the same tool) should be fine as long as you don't copy and paste some randomconv=flag from the Internet that is not suitable for your case. (@r2d3 that's why "sector-to-sector" can be vague)– Tom YanCommented Jan 28, 2022 at 19:46 -
1@dagna On Linux it's actually possible to use e.g.
losetup -P -b 4096 -f --show /dev/sdXto create a loop device of 4096-byte logical block size (kind of like emulating the original enclosure) on the drive. You will be able to access the data correctly via that without cloning. No idea if Windows has similar facility.– Tom YanCommented Jan 28, 2022 at 20:13