ceph/doc/mgr/osd_support.rst

   1 OSD Support Module
   2 ==================
   3 The OSD Support module holds osd specific functionality that
   4 is needed by different components like the orchestrators.
   5
   6 In current scope:
   7
   8 * osd draining
   9
  10 Enabling
  11 --------
  12 When an orchestrator is used this should be enabled as a dependency.
  13 (*currently only valid for the cephadm orchestrator*)
  14
  15 The *osd_support* module is manually enabled with::
  16
  17   ceph mgr module enable osd_support
  18
  19 Commands
  20 --------
  21
  22 Draining
  23 ########
  24
  25 This mode is for draining OSDs gracefully. `Draining` in this context means gracefully emptying out OSDs by setting their
  26 weight to zero. An OSD is considered to be drained when no PGs are left.
  27
  28 ::
  29
  30   ceph osd drain $osd_id
  31
  32 Takes a $osd_id and schedules it for draining. Since that process can take
  33 quite some time, the operation will be executed in the background. To query the status
  34 of the operation you can use:
  35
  36 ::
  37
  38   ceph osd drain status
  39
  40 This gives you the status of all running operations in this format::
  41
  42   [{'osd_id': 0, 'pgs': 1234}, ..]
  43
  44 If you wish to stop an OSD from being drained::
  45
  46   ceph osd drain stop [$osd_id]
  47
  48 Stops all **scheduled** osd drain operations (not the operations that have been started already)
  49 if no $osd_ids are given. If $osd_ids are present it only operates on them.
  50 To stop and reset the weight of already started operations we need to save the initial weight
  51 (see 'Ideas for improvement')
  52
  53
  54 Ideas for improvement
  55 ----------------------
  56 - add health checks set_health_checks
  57 - use objects to represent OSDs
  58   - allows timestamps, trending information etc
  59 - save osd drain state (at least the osd_ids in the mon store)
  60   - resume after a mgr crash
  61   - save the initial weight of a osd i.e. (set to initial weight on abort)