TODO

   1
   2 - check superblock checksum in examine DONE
   3 - report "chunk" or "rounding" depending on raid level DONE
   4 - report "linear" instead of "-1" for raid level DONE
   5 - decode ayout depending on raid level DONE
   6 - --verbose and --force flags.
   7
   8 - set md_minor, *_disks for Create  - DONE
   9 - for create raid5, how to choose between
  10    all working, but not insync
  11    one missing, one spare, insync
  12 - and for raid1 - some failed drives...
  13
  14 - when RUN_ARRAY, make sure *_disks counts are right
  15
  16 - get --detail to extract extra stuff from superblock,
  17    like uuid  DONE
  18 - --detail --brief to give a config file line
  19 - parse config file. DONE
  20 - test...
  21
  22 - when --assemble --scan, if an underlying device is an md device,
  23   then try to assemble that device first.
  24
  25
  26 - mdctl -S /dev/md0 /dev/md1 gives internal error
  27
  28 - mdctl --detail --scan print summary of what it can find?
  29
  30
  31 ---------
  32 Assemble doesn't add spares. - DONE
  33 Create to allow "missing" name for devices.
  34 Create to accept "--force" for do exactly what is requested
  35 - get Assemble to upgrade devices if force flag.
  36 ARRAY lines in config file to have super_minor=n
  37 ARRAY lines in config file to have device=pattern, and only accept
  38    those devices
  39    If UUID given, insist on that
  40    If not, but super_minor given, require all found with that minor
  41     to have same uuid
  42    If only device given, all valid supers on those devices must have
  43     same uuid
  44 allow /dev/mdX as first argument before any options
  45 Possible --dry-run option for create and assemble--force
  46
  47 Assemble to check that all devices mentioned in superblock
  48   are present.
  49
  50 New mode: --Monitor (or --Follow)
  51   Periodically check status of all arrays (listed in config file).
  52   Log every event and apparent cause - or differences
  53   Email and alert - or run a program - for important events
  54   Move spares around if necessary.
  55
  56   An Array line can have a spare-group= field that indicates that
  57    the array shares spares with other arrays with the same
  58    spare-group name.
  59    If an array has a failed and no spares, then check all other
  60      arrays in the spare group.  If one has no failures and a spare,
  61      then consider that spare.
  62     Choose the smallest considered spare that is large enough.
  63     If there is one, then hot-remove it from it's home, and
  64     hot-add it to the array in question.
  65
  66   --mail-to address
  67   --alert-handler program
  68
  69   Will also extract information from /proc/mdstat if present,
  70   and consider 20% marks in rebuild as events.
  71
  72   Events are:
  73      drive fails  - causes mail to be sent
  74      rebuild started
  75      spare activated
  76      spare removed
  77      spare added