[Bug 571653] Re: existing raid superblocks confuse/break the install

[Dmitrijs Ledkovs]

** Changed in: partman-md (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/571653

Title:
  existing raid superblocks confuse/break the install

Status in partman-md:
  New
Status in “partman-md” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: partman-md

  Partman fails if you try to set up raid with existing raid superblocks
  on some devices. (i.e. on re-installs/updates, if you want to reuse or
  even if you deleted exsiting raid partitions/devices.)

  Partman may get confused as raid devices get set up after partman
  (re)creates a partition and it happens that there is an superblock (at
  the beginning or end). Udev/mdadm sets it (partially) up and devices
  are in use.

  The common workaround suggested is to make sure to allways "mdadm
  --zero-superblock" raid partitions/devices prior to deleting them, or
  to to "just zero the entire disk between reinstallation attempts"
  (often heard after bad experiences).

  But partman-md should probably really watch out for/expect to see md
  devices being set up, (with udev/mdadm even after booting) and take
  them into account. (list them, offer to --stop, re-assemble (use) them
  as a real non-auxiliary device (not md127 and up),  --zero-superblock
  if needed, ...)

  related:
  Bug #22301
  Bug #33117
  Bug #569900

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