diff options
Diffstat (limited to 'src/ceph/doc/dev/ceph-volume/lvm.rst')
| -rw-r--r-- | src/ceph/doc/dev/ceph-volume/lvm.rst | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/src/ceph/doc/dev/ceph-volume/lvm.rst b/src/ceph/doc/dev/ceph-volume/lvm.rst new file mode 100644 index 0000000..f89424a --- /dev/null +++ b/src/ceph/doc/dev/ceph-volume/lvm.rst @@ -0,0 +1,127 @@ + +.. _ceph-volume-lvm-api: + +LVM +=== +The backend of ``ceph-volume lvm`` is LVM, it relies heavily on the usage of +tags, which is a way for LVM to allow extending its volume metadata. These +values can later be queried against devices and it is how they get discovered +later. + +.. warning:: These APIs are not meant to be public, but are documented so that + it is clear what the tool is doing behind the scenes. Do not alter + any of these values. + + +.. _ceph-volume-lvm-tag-api: + +Tag API +------- +The process of identifying logical volumes as part of Ceph relies on applying +tags on all volumes. It follows a naming convention for the namespace that +looks like:: + + ceph.<tag name>=<tag value> + +All tags are prefixed by the ``ceph`` keyword do claim ownership of that +namespace and make it easily identifiable. This is how the OSD ID would be used +in the context of lvm tags:: + + ceph.osd_id=0 + + +.. _ceph-volume-lvm-tags: + +Metadata +-------- +The following describes all the metadata from Ceph OSDs that is stored on an +LVM volume: + + +``type`` +-------- +Describes if the device is a an OSD or Journal, with the ability to expand to +other types when supported (for example a lockbox) + +Example:: + + ceph.type=osd + + +``cluster_fsid`` +---------------- +Example:: + + ceph.cluster_fsid=7146B649-AE00-4157-9F5D-1DBFF1D52C26 + +``data_device`` +--------------- +Example:: + + ceph.data_device=/dev/ceph/data-0 + +``journal_device`` +------------------ +Example:: + + ceph.journal_device=/dev/ceph/journal-0 + +``encrypted`` +------------- +Example for enabled encryption with ``luks``:: + + ceph.encrypted=luks + +For plain dmcrypt:: + + ceph.encrypted=dmcrypt + +For disabled encryption:: + + ceph.encrypted=0 + +``osd_fsid`` +------------ +Example:: + + ceph.osd_fsid=88ab9018-f84b-4d62-90b4-ce7c076728ff + +``osd_id`` +---------- +Example:: + + ceph.osd_id=1 + +``block`` +--------- +Just used on :term:`bluestore` backends. + +Example:: + + ceph.block=/dev/mapper/vg-block-0 + +``db`` +------ +Just used on :term:`bluestore` backends. + +Example:: + + ceph.db=/dev/mapper/vg-db-0 + +``wal`` +------- +Just used on :term:`bluestore` backends. + +Example:: + + ceph.wal=/dev/mapper/vg-wal-0 + + +``lockbox_device`` +------------------ +Only used when encryption is enabled, to store keys in an unencrypted +volume. + +Example:: + + ceph.lockbox_device=/dev/mapper/vg-lockbox-0 |