obligatory mdadm.conf ?

[Ratiu Petru <petre@lsd.ro>]

Hello Debian users,

I noticed that recent mdadm packages require the presence of mdadm.conf, at
least for the boot process. As a user of mdadm, I've used a few tricks I'm
not very sure that are still permitted:

* Changing order of drives
  Especially with SATA drives, it's very easy to lose the connection order
  so I made great use of the drive order detection, helped by a smart
  bootloader that uses whatever drive is first for all operations, of course
  with root raid1. Will the drive order change conflict with the order from
  mdadm.conf?

* Arrays with missing members
  When converting from non-raid boot to raid boot, i would create arrays
  with missing members instead of the active partitions, copy everything to
  the array, reboot to raid, complete the array, synchronize, profit! I'm
  not sure at what steps i will have to rebuild mdadm.conf and initrd.

* Recover from live CD
  I often found myself booting with Knoppix, modprobing md and raid*, doing
  a mdrun, creating the md devices (although i hear udev should do it from
  now on), mounting the arrays and doing the recovery. Will this be possible
  anymore without having a prepared mdadm.conf? More importantly, will the
  RAID superblocks be compatible with older or newer mdadm binaries or
  kernel modules?

Also, at this time the only way I'm confident of rebuilding mdadm.conf is by
dpkg-reconfigure mdadm. Is there some sort of update-mdadm script to do
this?

Sorry for the lengthy mail, but I couldn't get enough info from the packages'
documentation in order to predict how such scnarios will be affected in the
future.