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doc: update osd scenario 

This commits adds documentation for the lvm scenario and the deprecation
of collocated and non-collocated scenario.

Signed-off-by: Sébastien Han <seb@redhat.com>
pull/3851/head
Sébastien Han 2018-10-10 15:38:27 -04:00 committed by Dimitri Savineau
parent 52df15895b
commit f8e1542423
1 changed files with 14 additions and 191 deletions
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203
docs/source/osds/scenarios.rst
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@ -1,21 +1,25 @@
OSD Scenarios OSD Scenario
============= ============
There are a few *scenarios* that are supported and the differences are mainly As of stable-3.2, the following scenarios are not supported anymore since they are associated to ``ceph-disk``:
based on the Ceph tooling required to provision OSDs, but can also affect how
devices are being configured to create an OSD.
* `collocated`
* `non-collocated`
``ceph-disk`` was deprecated during the ceph-ansible 3.2 cycle and has been removed entirely from Ceph itself in the Nautilus version.
Supported values for the required ``osd_scenario`` variable are: Supported values for the required ``osd_scenario`` variable are:
* :ref:`collocated <osd_scenario_collocated>` At present (starting from stable-3.2), there is only one scenario, which defaults to ``lvm``, see:
* :ref:`non-collocated <osd_scenario_non_collocated>`
* :ref:`lvm <osd_scenario_lvm>` * :ref:`lvm <osd_scenario_lvm>`
Since the Ceph mimic release, it is preferred to use the :ref:`lvm scenario So there is no need to configure ``osd_scenario`` anymore, it defaults to ``lvm``.
Since the Ceph luminous release, it is preferred to use the :ref:`lvm scenario
<osd_scenario_lvm>` that uses the ``ceph-volume`` provisioning tool. Any other <osd_scenario_lvm>` that uses the ``ceph-volume`` provisioning tool. Any other
scenario will cause deprecation warnings. scenario will cause deprecation warnings.
All the scenarios mentionned above support both containerized and non-containerized cluster. The ``lvm`` scenario mentionned above support both containerized and non-containerized cluster.
As a reminder, deploying a containerized cluster can be done by setting ``containerized_deployment`` As a reminder, deploying a containerized cluster can be done by setting ``containerized_deployment``
to ``True``. to ``True``.
@ -235,184 +239,3 @@ Supported ``lvm_volumes`` configuration settings:
journal_vg: journal-vg2 journal_vg: journal-vg2
.. note:: Volume groups and logical volumes must exist. .. note:: Volume groups and logical volumes must exist.
.. _osd_scenario_collocated:
collocated
----------
.. warning:: This scenario is deprecated in the Ceph mimic release, and fully
removed in newer releases. It is recommended to used the
:ref:`lvm scenario <osd_scenario_lvm>` instead
This OSD scenario uses ``ceph-disk`` to create OSDs with collocated journals
from raw devices.
Use ``osd_scenario: collocated`` to enable this scenario. This scenario also
has the following required configuration options:
- ``devices``
This scenario has the following optional configuration options:
- ``osd_objectstore``: defaults to ``filestore`` if not set. Available options are ``filestore`` or ``bluestore``.
You can only select ``bluestore`` if the Ceph release is luminous or greater.
- ``dmcrypt``: defaults to ``false`` if not set.
This scenario supports encrypting your OSDs by setting ``dmcrypt: True``.
If ``osd_objectstore: filestore`` is enabled both 'ceph data' and 'ceph journal' partitions
will be stored on the same device.
If ``osd_objectstore: bluestore`` is enabled 'ceph data', 'ceph block', 'ceph block.db', 'ceph block.wal' will be stored
on the same device. The device will get 2 partitions:
- One for 'data', called 'ceph data'
- One for 'ceph block', 'ceph block.db', 'ceph block.wal' called 'ceph block'
Example of what you will get:
.. code-block:: console
[root@ceph-osd0 ~]# blkid /dev/sda*
/dev/sda: PTTYPE="gpt"
/dev/sda1: UUID="9c43e346-dd6e-431f-92d8-cbed4ccb25f6" TYPE="xfs" PARTLABEL="ceph data" PARTUUID="749c71c9-ed8f-4930-82a7-a48a3bcdb1c7"
/dev/sda2: PARTLABEL="ceph block" PARTUUID="e6ca3e1d-4702-4569-abfa-e285de328e9d"
An example of using the ``collocated`` OSD scenario with encryption would look like:
.. code-block:: yaml
osd_scenario: collocated
dmcrypt: true
devices:
- /dev/sda
- /dev/sdb
.. _osd_scenario_non_collocated:
non-collocated
--------------
.. warning:: This scenario is deprecated in the Ceph mimic release, and fully
removed in newer releases. It is recommended to used the
:ref:`lvm scenario <osd_scenario_lvm>` instead
This OSD scenario uses ``ceph-disk`` to create OSDs from raw devices with journals that
exist on a dedicated device.
Use ``osd_scenario: non-collocated`` to enable this scenario. This scenario also
has the following required configuration options:
- ``devices``
This scenario has the following optional configuration options:
- ``dedicated_devices``: defaults to ``devices`` if not set
- ``osd_objectstore``: defaults to ``filestore`` if not set. Available options are ``filestore`` or ``bluestore``.
You can only select ``bluestore`` with the Ceph release is luminous or greater.
- ``dmcrypt``: defaults to ``false`` if not set.
This scenario supports encrypting your OSDs by setting ``dmcrypt: True``.
If ``osd_objectstore: filestore`` is enabled 'ceph data' and 'ceph journal' partitions
will be stored on different devices:
- 'ceph data' will be stored on the device listed in ``devices``
- 'ceph journal' will be stored on the device listed in ``dedicated_devices``
Let's take an example, imagine ``devices`` was declared like this:
.. code-block:: yaml
devices:
- /dev/sda
- /dev/sdb
- /dev/sdc
- /dev/sdd
And ``dedicated_devices`` was declared like this:
.. code-block:: yaml
dedicated_devices:
- /dev/sdf
- /dev/sdf
- /dev/sdg
- /dev/sdg
This will result in the following mapping:
- ``/dev/sda`` will have ``/dev/sdf1`` as journal
- ``/dev/sdb`` will have ``/dev/sdf2`` as a journal
- ``/dev/sdc`` will have ``/dev/sdg1`` as a journal
- ``/dev/sdd`` will have ``/dev/sdg2`` as a journal
If ``osd_objectstore: bluestore`` is enabled, both 'ceph block.db' and 'ceph block.wal' partitions will be stored
on a dedicated device.
So the following will happen:
- The devices listed in ``devices`` will get 2 partitions, one for 'block' and one for 'data'. 'data' is only 100MB
big and do not store any of your data, it's just a bunch of Ceph metadata. 'block' will store all your actual data.
- The devices in ``dedicated_devices`` will get 1 partition for RocksDB DB, called 'block.db' and one for RocksDB WAL, called 'block.wal'
By default ``dedicated_devices`` will represent block.db
Example of what you will get:
.. code-block:: console
[root@ceph-osd0 ~]# blkid /dev/sd*
/dev/sda: PTTYPE="gpt"
/dev/sda1: UUID="c6821801-2f21-4980-add0-b7fc8bd424d5" TYPE="xfs" PARTLABEL="ceph data" PARTUUID="f2cc6fa8-5b41-4428-8d3f-6187453464d0"
/dev/sda2: PARTLABEL="ceph block" PARTUUID="ea454807-983a-4cf2-899e-b2680643bc1c"
/dev/sdb: PTTYPE="gpt"
/dev/sdb1: PARTLABEL="ceph block.db" PARTUUID="af5b2d74-4c08-42cf-be57-7248c739e217"
/dev/sdb2: PARTLABEL="ceph block.wal" PARTUUID="af3f8327-9aa9-4c2b-a497-cf0fe96d126a"
There is more device granularity for Bluestore ONLY if ``osd_objectstore: bluestore`` is enabled by setting the
``bluestore_wal_devices`` config option.
By default, if ``bluestore_wal_devices`` is empty, it will get the content of ``dedicated_devices``.
If set, then you will have a dedicated partition on a specific device for block.wal.
Example of what you will get:
.. code-block:: console
[root@ceph-osd0 ~]# blkid /dev/sd*
/dev/sda: PTTYPE="gpt"
/dev/sda1: UUID="39241ae9-d119-4335-96b3-0898da8f45ce" TYPE="xfs" PARTLABEL="ceph data" PARTUUID="961e7313-bdb7-49e7-9ae7-077d65c4c669"
/dev/sda2: PARTLABEL="ceph block" PARTUUID="bff8e54e-b780-4ece-aa16-3b2f2b8eb699"
/dev/sdb: PTTYPE="gpt"
/dev/sdb1: PARTLABEL="ceph block.db" PARTUUID="0734f6b6-cc94-49e9-93de-ba7e1d5b79e3"
/dev/sdc: PTTYPE="gpt"
/dev/sdc1: PARTLABEL="ceph block.wal" PARTUUID="824b84ba-6777-4272-bbbd-bfe2a25cecf3"
An example of using the ``non-collocated`` OSD scenario with encryption, bluestore and dedicated wal devices would look like:
.. code-block:: yaml
osd_scenario: non-collocated
osd_objectstore: bluestore
dmcrypt: true
devices:
- /dev/sda
- /dev/sdb
dedicated_devices:
- /dev/sdc
- /dev/sdc
bluestore_wal_devices:
- /dev/sdd
- /dev/sdd