Bug#543786: partman-auto-raid: having to name devices explicitly is clumsy

[Colin Watson <cjwatson@ubuntu.com>]

Package: partman-auto-raid
Version: 15
Severity: wishlist
Tags: patch
User: ubuntu-devel@lists.ubuntu.com
Usertags: origin-ubuntu ubuntu-patch karmic

partman-auto-raid/recipe currently has to be set like this:

d-i partman-auto-raid/recipe string \
  1 2 0 ext3 / /dev/sda1#/dev/sdb1 . \
  1 2 0 swap / /dev/sda5#/dev/sdb5 .

These device names would normally be expected to correspond to
partitions that are the result of running normal autopartitioning based
on partman-auto/expert_recipe or similar. I think that in general this
is clumsy and hard to manage. In particular, if you're generating
preseed files from some other format (e.g. kickseed) then it's
tremendously difficult to work out in advance what the partition numbers
are going to be in any portable way, without duplicating logic such as
that to choose default disk labels, due to the split between primary and
logical partitions; but even if you are in a position to work this out
by hand it is a very clumsy way to go about it.

Attached is a patch which introduces new syntax, looking like this:

d-i partman-auto-raid/recipe string \
  1 2 0 ext3 / raidid=1 . \
  1 2 0 swap / raidid=2 .

You then put raidid{ 1 } and raidid{ 2 } (the IDs don't have to be
numbers; they just have to contain neither spaces nor slashes) for the
method{ raid } elements in your main autopartitioning recipe, and
partman-auto-raid works out automatically which devices it ought to use.

Any comments? I think this is a noticeable improvement, so I'll commit
it next week or so if there are no objections.

Thanks,

-- 
Colin Watson                                       [cjwatson@ubuntu.com]