Hi all! Maybe someone with knowledge about xfs_repair can tell me, what could be the reason why a repair of an XFS partition is currently impossible. The backstory: one of our servers is running a VM with a proprietary service. After updating some packages on the host, the VM had crashed after running initially after the update. At next start the system in the VM (a rather old linux based on 2.2 kernel) could no longer boot complaining about invalid XFS structures. The VM is using a VMDK HD container. Using vmware-mount tools I detected that the VMDK container itself was also damaged. Vmware-tools could repair the container and I tried to mount the root partition which failed. I was able to locate the offset of the MBR inside the container and mounted a loop-back with that offset and using testdisk I was able to extract the partition with the root file system to a file. I also extracted two other partitions with this approach: another XFS and one EXT2. These two could be checked and fixed, but unfortunately the root filesystem is tricky. Maybe another information is important here: initially the system inside the VM was running on a native machine (about 10 years ago). The root fs was created as XFS on a software raid (/dev/md0). When I migrated the native machine to a VM I cloned the disks and later removed all but one of partitions of the disc array. Now I'm trying to fix the xfs in this partition dump. xfs_repair found 7 candidates of secondary superblocks, but is unable to verify them. I was rather disappointed with the lack of information xfs_repair reported. So I made a git clone of xfstools and looked for the code doing the repair and added some more output. I added information about the file offset of the candidates and the status, why it is considered unusable. The output of xfs_repair for my broken partition now looks like this: --- Phase 1 - find and verify superblock... bad primary superblock - bad magic number !!! attempting to find secondary superblock... found candidate secondary superblock... off: 32204029952 checking sbs#: 4 check sbs@ 32212221952 - status: 1 check sbs@ 64424443904 - status: 1 check sbs@ 96636665856 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 57813565440 checking sbs#: 4 check sbs@ 32212221952 - status: 1 check sbs@ 64424443904 - status: 1 check sbs@ 96636665856 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 64185663488 checking sbs#: 4 check sbs@ 32212221952 - status: 1 check sbs@ 64424443904 - status: 1 check sbs@ 96636665856 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 96412992512 checking sbs#: 4 check sbs@ 7232069632 - status: 1 check sbs@ 14464139264 - status: 1 check sbs@ 21696208896 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 96413164544 checking sbs#: 4 check sbs@ 7232069632 - status: 1 check sbs@ 14464139264 - status: 1 check sbs@ 21696208896 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 96413271040 checking sbs#: 4 check sbs@ 7232069632 - status: 1 check sbs@ 14464139264 - status: 1 check sbs@ 21696208896 - status: 1 unable to verify superblock, continuing... error code: 16 found candidate secondary superblock... off: 96419537920 checking sbs#: 4 check sbs@ 7232069632 - status: 1 check sbs@ 14464139264 - status: 1 check sbs@ 21696208896 - status: 1 unable to verify superblock, continuing... error code: 16 Sorry, could not find valid secondary superblock Exiting now. -- (error code 16: not enough superblocks to validate status code 1: invalid superblock signature) I also extracted the blocks at the given offsets (eg @ 32204029952) , examined them and the contents of the SSBs are looking quite good: -- 00000000 58 46 53 42 00 00 10 00 00 00 00 00 01 df ff e0 |XFSB............| 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000020 b1 f2 a8 ad 7d 75 4d a0 9a be 3f e6 a4 e4 05 c3 |....}uM...?.....| 00000030 00 00 00 00 01 00 00 04 00 00 00 00 00 00 00 80 |................| 00000040 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| 00000050 00 00 00 01 00 77 ff f8 00 00 00 04 00 00 00 00 |.....w..........| 00000060 00 00 3b ff b4 a4 02 00 01 00 00 10 68 79 00 00 |..;.........hy..| 00000070 00 00 00 00 00 00 00 00 0c 09 08 04 17 00 00 19 |................| 00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000090 00 00 00 00 01 df c3 d1 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 02 00 00 00 00 00 00 00 00 |................| 000000c0 00 00 00 00 00 00 00 01 00 00 00 08 00 00 00 08 |................| 000000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000200 -- As far as I understood, xfs_repair considers the file system unfixable, because the secondary superblocks are not found at the offsets, where they should be. The blocks found look quite ok. My guess: because the VMDK container got damaged, the information of the internal partitions is now incorrect, so testdisk did extract a file that is somehow broken. But from what I've seen so far, it could be possible to fix it up to the point, to extract some files. What is unclear for me: why are 7 SSB found? Is this a geometry issue? The found superblocks tell, that a total of 4 superblocks should exist. What happens if you grow an XFS file system? Do additional stripes generate a layout like this? Is the distance between the superblock copies ALWAYS a constant value? In my scenario the distance of the first 3 superblocks is not a fixed value. But how can blocks get lost? I don't think this is possible with VMDK to "mark blocks as deleted" inside a partition and they are skipped when reading a partition. Perhaps somebody with more knowledge can comment on this and can give me some pointers. 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