ceph/doc/dev/ceph-disk.rst
Kefu Chai 05da6d34be doc/dev/ceph-disk: add docs for ceph-disk
we might want to move part of it to user-facing docs.

Signed-off-by: Kefu Chai <kchai@redhat.com>
2017-07-25 00:21:05 +08:00

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=========
ceph-disk
=========
device-mapper crypt
===================
Settings
--------
``osd_dmcrypt_type``
:Description: this option specifies the mode in which ``cryptsetup`` works. It can be ``luks`` or ``plain``. It kicks in only if the ``--dmcrypt`` option is passed to ``ceph-disk``. See also `cryptsetup document <https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt#configuration-using-cryptsetup>`_ for more details.
:Type: String
:Default: ``luks``
``osd_dmcrypt_key_size``
:Description: the size of the random string in bytes used as the LUKS key. The string is read from ``/dev/urandom`` and then encoded using base64. It will be stored with the key of ``dm-crypt/osd/$uuid/luks`` using config-key.
:Type: String
:Default: 1024 if ``osd_dmcrypt_type`` is ``luks``, 256 otherwise.
lockbox
-------
``ceph-disk`` supports dmcrypt (device-mapper crypt). If dmcrypt is enabled, the partitions will be encrypted using this machinary. For each OSD device, a lockbox is introduced for holding the information regarding how the dmcrypt key is stored. To prepare a lockbox, ``ceph-disk``
#. creates a dedicated lockbox partition on device, and
#. populates it with a tiny filesystem, then
#. automounts it at ``/var/lib/ceph/osd-lockbox/$uuid``, read-only. where the ``uuid`` is the lockbox's uuid.
under which, settings are stored using plain files:
- key-management-mode: ``ceph-mon v1``
- osd-uuid: the OSD's uuid
- ceph_fsid: the fsid of the cluster
- keyring: the lockbox's allowing one to fetch the LUKS key
- block_uuid: the partition uuid for the block device
- journal_uuid: the partition uuid for the journal device
- block.db_uuid: the partition uuid for the block.db device
- block.wal_uuid: the partition uuid for the block.wal device
- magic: a magic string indicating that this partition is a lockbox. It's not used currently.
- ``${space_uuid}``: symbolic links named after the uuid of space partitions pointing to ``/var/lib/ceph/osd-lockbox/$uuid``. in the case of FileStore, the space partitions are ``data`` and ``journal`` partitions, for BlueStore, they are ``data``, ``block.db`` and ``block.wal``.
Currently, ``ceph-mon v1`` is the only supported key-management-mode. In that case, the LUKS key is stored using the config-key in the monitor store with the key of ``dm-crypt/osd/$uuid/luks``.
partitions
==========
``ceph-disk`` creates partitions for preparing a device for OSD deployment. Their partition numbers are hardcoded. For instance, data partition's partition number is always *1* :
1. data partition
2. journal partition, if co-located with data
3. block.db for BlueStore, if co-located with data
4. block.wal for BlueStore, if co-located with data
5. lockbox