mirror of https://github.com/ceph/ceph
180 lines
3.4 KiB
ReStructuredText
180 lines
3.4 KiB
ReStructuredText
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.. _ceph-volume-lvm-api:
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LVM
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===
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The backend of ``ceph-volume lvm`` is LVM, it relies heavily on the usage of
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tags, which is a way for LVM to allow extending its volume metadata. These
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values can later be queried against devices and it is how they get discovered
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later.
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.. warning:: These APIs are not meant to be public, but are documented so that
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it is clear what the tool is doing behind the scenes. Do not alter
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any of these values.
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.. _ceph-volume-lvm-tag-api:
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Tag API
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-------
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The process of identifying logical volumes as part of Ceph relies on applying
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tags on all volumes. It follows a naming convention for the namespace that
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looks like::
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ceph.<tag name>=<tag value>
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All tags are prefixed by the ``ceph`` keyword to claim ownership of that
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namespace and make it easily identifiable. This is how the OSD ID would be used
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in the context of lvm tags::
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ceph.osd_id=0
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.. _ceph-volume-lvm-tags:
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Metadata
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--------
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The following describes all the metadata from Ceph OSDs that is stored on an
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LVM volume:
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``type``
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--------
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Describes if the device is an OSD or Journal, with the ability to expand to
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other types when supported (for example a lockbox)
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Example::
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ceph.type=osd
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``cluster_fsid``
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----------------
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Example::
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ceph.cluster_fsid=7146B649-AE00-4157-9F5D-1DBFF1D52C26
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``data_device``
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---------------
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Example::
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ceph.data_device=/dev/ceph/data-0
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``data_uuid``
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-------------
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Example::
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ceph.data_uuid=B76418EB-0024-401C-8955-AE6919D45CC3
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``journal_device``
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------------------
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Example::
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ceph.journal_device=/dev/ceph/journal-0
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``journal_uuid``
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----------------
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Example::
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ceph.journal_uuid=2070E121-C544-4F40-9571-0B7F35C6CB2B
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``encrypted``
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-------------
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Example for enabled encryption with ``luks``::
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ceph.encrypted=1
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When encryption is not supported or simply disabled::
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ceph.encrypted=0
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``osd_fsid``
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------------
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Example::
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ceph.osd_fsid=88ab9018-f84b-4d62-90b4-ce7c076728ff
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``osd_id``
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----------
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Example::
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ceph.osd_id=1
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``block_device``
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----------------
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Just used on :term:`bluestore` backends. Captures the path to the logical
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volume path.
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Example::
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ceph.block_device=/dev/mapper/vg-block-0
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``block_uuid``
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--------------
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Just used on :term:`bluestore` backends. Captures either the logical volume UUID or
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the partition UUID.
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Example::
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ceph.block_uuid=E5F041BB-AAD4-48A8-B3BF-31F7AFD7D73E
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``db_device``
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-------------
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Just used on :term:`bluestore` backends. Captures the path to the logical
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volume path.
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Example::
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ceph.db_device=/dev/mapper/vg-db-0
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``db_uuid``
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-----------
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Just used on :term:`bluestore` backends. Captures either the logical volume UUID or
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the partition UUID.
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Example::
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ceph.db_uuid=F9D02CF1-31AB-4910-90A3-6A6302375525
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``wal_device``
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--------------
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Just used on :term:`bluestore` backends. Captures the path to the logical
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volume path.
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Example::
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ceph.wal_device=/dev/mapper/vg-wal-0
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``wal_uuid``
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------------
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Just used on :term:`bluestore` backends. Captures either the logical volume UUID or
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the partition UUID.
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Example::
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ceph.wal_uuid=A58D1C68-0D6E-4CB3-8E99-B261AD47CC39
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``vdo``
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-------
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A VDO-enabled device is detected when device is getting prepared, and then
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stored for later checks when activating. This affects mount options by
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appending the ``discard`` mount flag, regardless of mount flags being used.
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Example for an enabled VDO device::
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ceph.vdo=1
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