Is there a way to move an ext4 filesystem between physical disks transparently for the applications, i.e. while preserving file descriptors? There's no LVM nor hardware RAID, unfortunately.

I was thinking in the direction of creating an md mirror and breaking it after the sync, but it seems that it requires unmounting the disk or partition at least once. Converting to LVM on the fly would be ideal, but I haven't found any evidence that it can be done.

  • Probably not. Things like LVM exist exactly for that kind of stuff, and as you suggested, a MD mirror can be used for a similar purpose.
    – ilkkachu
    Mar 22, 2021 at 17:06
  • It believe it is possible to use dmsetup directly to create a mirror on a device without unmounting it, rather than using the LVM wrappers to do this. Unfortunately, I don't know the exact commands, or I would make this an answer instead of a comment.
    – LustreOne
    Mar 22, 2021 at 20:26

1 Answer 1


Nope; you have to have set up your disks to use LVM in order to do this. Or use btrfs.

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