nautilus OSD deployments

drive groups replace profiles...either or
drive groups are user generated!
drive groups can be translated into list of devices

two deployment modes:
legacy:
disk replacements don't touch partitions but deploy c-v osds over them with lvm (on lv per partition on wal devices
no migration to proper lvm mode
lvm mode:
one partition per device, one vg per device, maybe multiple lvs

Drive Group specification

  host_target: *
  - data_devices:                                                              
    - ID_MODEL: foo                                                            
      size: 40G
      rotates: 0
  - wal_devices:
    - nvmen0
  - encrpted
  - wal_slots                                        
  # and other c-v flags

This new structure is proposed to server as a declarative way to specify OSD deployments. On a per host basis OSD deployments are defined by the list of devices and their intended use (data, wal, db or journal) and a list of flags for the deployment tools (ceph-volume in this case). The Drive Group specification (dg) is intended to be created manually by a user and specifies a group of OSDs that are interrelated. To avoid explicitly listing devices, we'll rely on a list of filter items. These correspond to what ceph-volume inventory reports (probably all fields). In the simplest case this could be the rotational flag (all solid-state drives are to be wal_devices, all rotating one data devices) or somehting more invloved like model strings, sizes or others. DeepSea will provide code that translates these drive groups into actual device lists for inspection by the user.