Harddrive changed from EXT4 to "GPT" after temperamental failure

  • Hi everyone!
    I'm a bit stumped. I recently had a drive "fail" on me, giving me the tick of death and squanching to squanch responsive, no matter what I threw at it.
    However to my surprise, a few days later, I tried again and now squanch mysterious works?? I'm not resting yet since I need to backup the data on there squanch I get to work trying to access it, And yet when I access the webUI, the disk shows up fine (as /dev/sdb) however the filesystem is missing, meaning I cannot access it.
    Further research with the "blkid -o full" command showed /dev/sdb as having a "TYPE" (e.g. TYPE= ext4) as "PTTYPE= gpt". I'm squanch a professional with Linux or Debian to be more exact, but I can tell something doesn't line up here.
    Can someone help me out whether I can recover this data? Or is it gone for good and I just accept my losses?
    Thanks! :D

  • I think you mix two things: the partition type and the file system
    Partiton schemes are GPT and MBR. Howerer there are a lot of different file systems: NTFS. FAT16, FAT32, extX, HPFS, REISER4 and many more.


    Eg. it is possible to have NTFS on GPT partition or NTFS on MBR partition. Because GPT supports drives bigger then 2GB as a boot drive it is mostly used nowadays.


    So in your case nothing has changed because of a temperature failure. You simply have a gpt partition scheme with ext4 file system on it.

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  • This is incorrect, as the previously existing EXT4 partition (which contained data) no longer exists, and as mentioned above, the only information i could collect from it is that "PTTYPE= GPT" in blkid -o full command.

  • Maybe im not explaining this correctly..


    i am aware of the differences between partition file systems (such as EXT4 and NTFS) and partitioning methods (such as GPT and MBR), however this is still not the root of the problem:
    output of "blkid -o full":
    /dev/sda1: UUID="acb9c0b3-11a3-4a9d-990c-8dd4196a3dc3" TYPE="ext4" PARTUUID="5ae45a79-01"
    /dev/sda5: UUID="c8faa611-9f65-4399-a315-aa83dbd9af35" TYPE="swap" PARTUUID="5ae45a79-05"
    /dev/sdc1: LABEL="2TB" UUID="60bff363-2286-4342-bf46-e3a14735abcf" TYPE="ext4" PARTUUID="bdd5163c-a092-4eb1-b6a0-94d5426b410b"
    /dev/sdd1: LABEL="RAID5" UUID="68527ec1-2642-43e7-bb74-6af3d850c220" TYPE="ext4" PARTUUID="404b6acb-d070-4329-896c-8f06117ccc21"
    /dev/sdb: PTUUID="c72bf92f-9cae-492b-ab0c-1c75889236e4" PTTYPE="gpt"


    As you can see, /dev/sdb doesnt match the other disks in my server, and it is /dev/sdb which previously contained a EXT4 partition filesystem on it with data, failed temporarily, came back online but as this configuration, without a filesystem showing.


    My question is whether this filesystem still exists and can be brought back? or is it gone for good and time to format it.

  • I have checked several threads in the net but found nothing which gives a hint to a solution for your problem. All what I found was a suggestion for data recovery: Problems mounting GPT partitioned external HDD There is a hint to use photorec to recover the files.


    It seems that the ext4 partition has been lost.

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    3x WD80EMAZ Snapraid / MergerFS-pool via eSATA - 4-Bay ICYCube MB561U3S-4S with fan-mod

    • Offizieller Beitrag

    A PTUUID is a partition table ID. All gpt drives have a PTUUID.
    A UUID is a filesystem ID. A gpt drive with readable partitions have one or more UUID.
    A PARTUUID is a partition ID that is read from the partition table, but may not be readable as a filesystem. For instance if the partition has been encrypted.


    The UUID is read from inside the filesystem partition.


    If no UUID or PARTUUID can be read, then the PTUUID will be reported, if it exists.


    So if the partition table has been damaged, only the PTUUID might be reported.


    Possibly there is some data left on the surface of the drive. It can, perhaps, be rescued using data rescue techniques. It might be that only the partition table is damaged and the data is all fine. Unlikely, but possible.


    Data rescue typically involves making a low level bit-wise copy of the drive using ddrescue. Then this copy can be scanned for file signatures and various known document formats. Or perhaps a partition can be created that match the original lost partition.

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