Re: [Patch] mdadm ignoring homehost?

[Neil Brown <neilb@suse.de>]

On Saturday April 18, dledford@redhat.com wrote:
> 
> I've been thinking about this, and this is the method I would suggest.
> 
> Add two new keywords to the mdadm.conf file:
> 
> ASSEMBLE
> INCREMENTAL
> 
> Allow each of those keywords to have one of three set values:
> None - Don't attempt to assemble any arrays regardless of whether or  
> not they are in the mdadm.conf file or not
> Known - Only assemble arrays with a matching array line
> All - Attempt to assemble any array found
> 
> The combination of the two options and the three settings would allow  
> you to control mdadm behavior for both array assembly modes  
> independently.  That, combined with my previous patch, should allow  
> arrays to assemble well, with known names, allow you to control auto  
> assembly by udev, and in the event that your machine just exports  
> volumes to other machines for their use, stop assembly entirely.

Why "None"??  Why would you use "None" rather than "Known" with an
empty list of arrays?

Why have two options: ASSEMBLE and INCREMENTAL ??
If what circumstance would you use different settings for these two
options.

I current have two patches sitting in my scratch queue.  I am by no
means committed to them.

One allows you to have e.g.

  ARRAY ignore UUID=foo:bar:dead:beef

with the meaning that auto-assembly will ignore that array.  If you
run

  mdadm --assemble /dev/md/thing --uuid foo:bar:dead:beef

it will still assemble the array, but any auto-assembly will ignore
it.

The other allows you to say:

 AUTO -ddf -0.90 +all

which means don't auto-assemble any 'ddf' or '0.90' array, but do
auto-assemble anything else that is recognised.
You might want to use dmraid for ddf??

If you just have

  AUTO -all

then it won't auto-assemble anything, which is much like your
  ASSEMBLE  Known
  INCREMENTAL Known

NeilBrown