Incremental: remove partitions when assembling.

We remove partitions for --create and --assemble, but not for
--incrmental.
So fix that ommision.

Signed-off-by: NeilBrown <neilb@suse.de>
create_mddev: add support for /dev/md_XXX non-numeric names.

With the 'devnm' infrastructure fixed, it is quite easy to support
names like "md_home" for md arrays.
The currently defaults to "off" and can be enabled in mdadm.conf with
  CREATE names=yes
This is incase other tools get confused by the new names.

Signed-off-by: NeilBrown <neilb@suse.de>
man pages: remove references to raidtools.

raidtools is so ancient now that it is uninteresting.

Signed-off-by: NeilBrown <neilb@suse.de>
Suppress error messages from systemctl.

We call systemctl to see if systemd will run mdmon for us.
If it cannot, we run mdmon directly, so we aren't interested
in the error message.
So redirect stderr to /dev/null.

Signed-off-by: NeilBrown <neilb@suse.de>
Create: over-ride "start_ro" setting when creating an array.

If module parameter start_ro is set, arrays start readonly.
This is OK when assembling, but is very surprising when creating
an array as the resync won't start.
So over-ride the setting (unless --read-only was given) make
arrays RW when created.

Signed-off-by: NeilBrown <neilb@suse.de>
intel,ddf: don't require partitions when ignore_hw_compat is set.

Partitions are a hw-compat issue.

This allows e.g "--examine" to be used on image files.

Signed-off-by: NeilBrown <neilb@suse.de>
Add --dump / --restore functionality.

This allows the metadata on a device to be saved and later restored.
This can be useful before experimenting on an array that is misbehaving.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>