Comment 14 for bug 1893661

> I think your suggestion is a good YAML scheme. I think size_kb:
> should be optional to fill the whole array with one volume if
> it's omitted.

Well, it's not that simple. What do we do if it's omitted and
the config includes multiple volumes from the same container?

Curtin config is typically constructed from an "Oracle"; either
MAAS or Subiquity probe storage and then provide complete
configuration from user-input.

So if either added support for VROC, they would know in advance
how many volumes per container and could specify the exact
size.

I believe we want to require size_kb if metadata == 'imsm'

> The number of devices can be looked up by pairing
> 'container' with 'id'.

Yes, I put the id anchor there so that the volumes created with
in a container will be able to lookup the correct value rather
than having to repeat.

> Maybe it would be possible to abstract out the container, like:
> - type: raid

Everything needs and id.

id: raid_container_0

> metadata: imsm
> container: /dev/md/imsm0

This isn't needed, IIUC, metadata=imsm implies a container
raid, no?

> name: imsm0

name: /dev/md/imsm0

> devices:
> - /dev/nvme0n1p1
> - /dev/nvme1n1p1
>
> - type: raid
> devices:
> - /dev/md/imsm0 # but need to get the number of real devices for -n

Yes, this is nice, and what we will do instead is:

devices:
  - raid_container_0

> name: mirror0
> level: 1

> I suggest to add a level: container to the top-level, as it would
> imply to use the -e switch to mdadm, and also would be consistent
> to the query output.
>
> - type: raid
> id: disk_raid_container0
> level: container
> metadata: imsm

I think we can skip that if it's true that imsm is always a
container.

> name: /dev/md/imsm0
> devices:
> - /dev/nvme0n1p1
> - /dev/nvme1n1p1

> Another buglet: metadata is not passed to mdadm_create() in
> raid_handler()

Good catch! And in that case we can always pass --metadata=
to mdadm, if metadata is not provided, we use the default.

Containers, of course, require metadata=imsm