ceph/doc/ceph-volume/lvm/activate.rst

   1 .. _ceph-volume-lvm-activate:
   2
   3 ``activate``
   4 ============
   5
   6 Once :ref:`ceph-volume-lvm-prepare` is completed, and all the various steps
   7 that entails are done, the volume is ready to get "activated".
   8
   9 This activation process enables a systemd unit that persists the OSD ID and its
  10 UUID (also called ``fsid`` in Ceph CLI tools), so that at boot time it can
  11 understand what OSD is enabled and needs to be mounted.
  12
  13 .. note:: The execution of this call is fully idempotent, and there is no
  14           side-effects when running multiple times
  15
  16 For OSDs deployed by cephadm, please refer to :ref:cephadm-osd-activate:
  17 instead.
  18
  19 New OSDs
  20 --------
  21 To activate newly prepared OSDs both the :term:`OSD id` and :term:`OSD uuid`
  22 need to be supplied. For example::
  23
  24     ceph-volume lvm activate --bluestore 0 0263644D-0BF1-4D6D-BC34-28BD98AE3BC8
  25
  26 .. note:: The UUID is stored in the ``fsid`` file in the OSD path, which is
  27           generated when :ref:`ceph-volume-lvm-prepare` is used.
  28
  29 Activating all OSDs
  30 -------------------
  31
  32 .. note:: For OSDs deployed by cephadm, please refer to :ref:cephadm-osd-activate:
  33           instead.
  34
  35 It is possible to activate all existing OSDs at once by using the ``--all``
  36 flag. For example::
  37
  38     ceph-volume lvm activate --all
  39
  40 This call will inspect all the OSDs created by ceph-volume that are inactive
  41 and will activate them one by one. If any of the OSDs are already running, it
  42 will report them in the command output and skip them, making it safe to rerun
  43 (idempotent).
  44
  45 requiring uuids
  46 ^^^^^^^^^^^^^^^
  47 The :term:`OSD uuid` is being required as an extra step to ensure that the
  48 right OSD is being activated. It is entirely possible that a previous OSD with
  49 the same id exists and would end up activating the incorrect one.
  50
  51
  52 dmcrypt
  53 ^^^^^^^
  54 If the OSD was prepared with dmcrypt by ceph-volume, there is no need to
  55 specify ``--dmcrypt`` on the command line again (that flag is not available for
  56 the ``activate`` subcommand). An encrypted OSD will be automatically detected.
  57
  58
  59 Discovery
  60 ---------
  61 With OSDs previously created by ``ceph-volume``, a *discovery* process is
  62 performed using :term:`LVM tags` to enable the systemd units.
  63
  64 The systemd unit will capture the :term:`OSD id` and :term:`OSD uuid` and
  65 persist it. Internally, the activation will enable it like::
  66
  67     systemctl enable ceph-volume@lvm-$id-$uuid
  68
  69 For example::
  70
  71     systemctl enable ceph-volume@lvm-0-8715BEB4-15C5-49DE-BA6F-401086EC7B41
  72
  73 Would start the discovery process for the OSD with an id of ``0`` and a UUID of
  74 ``8715BEB4-15C5-49DE-BA6F-401086EC7B41``.
  75
  76 .. note:: for more details on the systemd workflow see :ref:`ceph-volume-lvm-systemd`
  77
  78 The systemd unit will look for the matching OSD device, and by looking at its
  79 :term:`LVM tags` will proceed to:
  80
  81 # mount the device in the corresponding location (by convention this is
  82   ``/var/lib/ceph/osd/<cluster name>-<osd id>/``)
  83
  84 # ensure that all required devices are ready for that OSD. In the case of
  85 a journal (when ``--filestore`` is selected) the device will be queried (with
  86 ``blkid`` for partitions, and lvm for logical volumes) to ensure that the
  87 correct device is being linked. The symbolic link will *always* be re-done to
  88 ensure that the correct device is linked.
  89
  90 # start the ``ceph-osd@0`` systemd unit
  91
  92 .. note:: The system infers the objectstore type (filestore or bluestore) by
  93           inspecting the LVM tags applied to the OSD devices
  94
  95 Existing OSDs
  96 -------------
  97 For existing OSDs that have been deployed with ``ceph-disk``, they need to be
  98 scanned and activated :ref:`using the simple sub-command <ceph-volume-simple>`.
  99 If a different tooling was used then the only way to port them over to the new
 100 mechanism is to prepare them again (losing data). See
 101 :ref:`ceph-volume-lvm-existing-osds` for details on how to proceed.
 102
 103 Summary
 104 -------
 105 To recap the ``activate`` process for :term:`bluestore`:
 106
 107 #. require both :term:`OSD id` and :term:`OSD uuid`
 108 #. enable the system unit with matching id and uuid
 109 #. Create the ``tmpfs`` mount at the OSD directory in
 110    ``/var/lib/ceph/osd/$cluster-$id/``
 111 #. Recreate all the files needed with ``ceph-bluestore-tool prime-osd-dir`` by
 112    pointing it to the OSD ``block`` device.
 113 #. the systemd unit will ensure all devices are ready and linked
 114 #. the matching ``ceph-osd`` systemd unit will get started
 115
 116 And for :term:`filestore`:
 117
 118 #. require both :term:`OSD id` and :term:`OSD uuid`
 119 #. enable the system unit with matching id and uuid
 120 #. the systemd unit will ensure all devices are ready and mounted (if needed)
 121 #. the matching ``ceph-osd`` systemd unit will get started