Can anyone tell me the difference between the different metadata versions for mdadm?

When I try the command mdadm --examine /dev/sda1, I can't seem to find "preferred superblocks" on version 1.2. This field shows up in metadata version 0.9.

Is there a way to get such metadata information? Or is the output of mdadm --examine just the information I'm going to get for version 1.2?

1 Answer 1


All the differences are covered here RAID wiki on kernel.org. The page is titled: RAID superblock formats. The version 0.90 and 1.2 formats of the superblock are covered there as well.

The on-disk layouts are covered there as well.

  • There's no information about the metadata structure for 0.90 to compare them with. I'm trying find the "preferred minor" field but isn't found in the metadata for version 1.* from the document provided.
    – supmethods
    Commented Apr 9, 2014 at 3:03

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