mdadm for Debian - initramfs transition
=======================================

If you are using monolithic kernels (no modules), you need not concern
yourself with any of this.

If you are using yaird or initrd-tools/mkinitrd, please see README.mdrun. The
following information is irrelevant to you.

The following information is about #367567. The gist is that the hooks and
scripts to take care of MD arrays (RAIDs) during boot with an initramfs have
been improved and moved into the mdadm package. mdrun has been deprecated on
the way (see README.mdrun).

initramfs-tools does *not* conflict with older mdadm but instead provides
fallback code in case mdadm << 2.5-1 is installed (which does not provide the
hooks yet). This decision was made in order to prevent the slight chance that
mdadm would be removed due to the conflict. See #380089.

Unless I've overlooked a detail, no interaction is required from the side of
the user (apart from the new debconf question) to install and get mdadm
running and integrated with initramfs-tools. It helps to ensure that
update-initramfs produces output that squares with your own perception of what
is needed to boot, and that the output of the script /usr/share/mdadm/mkconf
is sane after installation and before you reboot.

Also, you may want to provide yourself a safety net by making a copy of the
initrd:

  cp /boot/initrd.img-$(uname -r) /boot/initrd.img-$(uname -r).before-mdadm2

and then to duplicate your main grub or lilo stanzas (rerun lilo!) and point
them to the saved initrd. If things go haywire, you should be able to restore
a working condition with the saved initrd.

If you want to move to the new hooks and scripts without installing
initramfs-tools 0.70, do this:

  rm /usr/share/initramfs-tools/hooks/md
  sed -i -e 's,^PREREQ=\"md\"$,PREREQ=\"mdadm\",' \
    /usr/share/initramfs-tools/scripts/local-top/lvm
  update-initramfs -u -k all

If update-initramfs says something about initrd having been altered and
refuses to do something, use -t unless you modified the initrd on purpose and
don't want it overwritten.

Again, please report success or failure to me.

 -- martin f. krafft <madduck@debian.org>  Mon, 23 Sep 2006 23:48:21 +0100

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