From d25a04114c98aa1449809248e8b87ecd1124af3d Mon Sep 17 00:00:00 2001 From: Alfredo Deza Date: Tue, 14 Nov 2017 11:01:48 -0500 Subject: [PATCH] doc/ceph-volume lvm prepare can accept devices for --data Signed-off-by: Alfredo Deza (cherry picked from commit 9bfab348b2ff59c0b939a19c22d4a06bc5236b96) Conflicts: doc/ceph-volume/lvm/prepare.rst --- doc/ceph-volume/lvm/prepare.rst | 41 ++++++++++++++++++++++++--------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/doc/ceph-volume/lvm/prepare.rst b/doc/ceph-volume/lvm/prepare.rst index dfb49c54efea3..27ebb55d7e628 100644 --- a/doc/ceph-volume/lvm/prepare.rst +++ b/doc/ceph-volume/lvm/prepare.rst @@ -33,17 +33,37 @@ the back end can be specified with: This is the OSD backend that allows preparation of logical volumes for a :term:`filestore` objectstore OSD. -The process is *very* strict, it requires an existing logical volume for the -OSD data and a partitioned physical device or logical volume for the journal. -No special preparation is needed for these volumes other than following the -minimum size requirements for data and journal. +It can use a logical volume for the OSD data and a partitioned physical device +or logical volume for the journal. No special preparation is needed for these +volumes other than following the minimum size requirements for data and +journal. The API call looks like:: ceph-volume prepare --filestore --data data --journal journal -The journal *must* be a logical volume, just like the data volume, and that -argument is always required even if both live under the same group. +There is flexibility to use a raw device or partition as well for ``--data`` +that will be converted to a logical volume. This is not ideal in all situations +since ``ceph-volume`` is just going to create a unique volume group and +a logical volume from that device. + +When using logical volumes for ``--data``, the value *must* be a volume group +name and a logical volume name separated by a ``/``. Since logical volume names +are not enforced for uniqueness, this prevents using the wrong volume. The +``--journal`` can be either a logical volume *or* a partition. + +When using a partition, it *must* contain a ``PARTUUID`` discoverable by +``blkid``, so that it can later be identified correctly regardless of the +device name (or path). + +When using a partition, this is how it would look for ``/dev/sdc1``:: + + ceph-volume prepare --filestore --data volume_group/lv_name --journal /dev/sdc1 + +For a logical volume, just like for ``--data``, a volume group and logical +volume name are required:: + + ceph-volume prepare --filestore --data volume_group/lv_name --journal volume_group/journal_lv A generated uuid is used to ask the cluster for a new OSD. These two pieces are crucial for identifying an OSD and will later be used throughout the @@ -115,11 +135,10 @@ more flexibility for devices. Bluestore supports the following configurations: * A block device and a block.db device * A single block device -It can accept a whole device (not a partition, otherwise it will raise an -error) or a logical volume for ``block``. If a physical device is provided it -will then be turned into a logical volume. This allows a simpler approach at -using LVM but at the cost of flexibility: there are no options or -configurations to change how the LV is created. +It can accept a whole device (or partition), or a logical volume for ``block``. +If a physical device is provided it will then be turned into a logical volume. +This allows a simpler approach at using LVM but at the cost of flexibility: +there are no options or configurations to change how the LV is created. The ``block`` is specified with the ``--data`` flag, and in its simplest use case it looks like:: -- 2.39.5