ceph-ansible/docs/source/osds/scenarios.rst

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OSD Scenarios
=============
The following are all of the available options for the ``osd_scenario`` config
setting. Defining an ``osd_scenario`` is mandatory for using ``ceph-ansible``.
collocated
----------
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
non-collocated
--------------
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
lvm
---
This OSD scenario uses ``ceph-volume`` to create OSDs from logical volumes and
is only available when the Ceph release is Luminous or newer.
Configurations
^^^^^^^^^^^^^^
``lvm_volumes`` or ``devices`` are the config option that needs to be defined to deploy OSDs
with the ``lvm`` osd scenario.
- ``lvm_volumes`` is a list of dictionaries which expects a volume name and a volume group for
logical volumes, but can also accept a partition in the case of ``filestore`` for the ``journal``.
If ``lvm_volumes`` is defined then the ``ceph-volume lvm create`` command is used to create each OSD
defined in ``lvm_volumes``.
- ``devices`` is a list of raw device names as strings. If ``devices`` is defined then the ``ceph-volume lvm batch``
command will be used to deploy OSDs. You can also use the ``osds_per_device`` variable to inform ``ceph-volume`` how
many OSDs it should create from each device it finds suitable.
Both ``lvm_volumes`` and ``devices`` can be defined and both methods would be used in the deployment or you
can pick just one method.
This scenario supports encrypting your OSDs by setting ``dmcrypt: True``. If set,
all OSDs defined in ``lvm_volumes`` will be encrypted.
The ``data`` key represents the logical volume name, raw device or partition that is to be used for your
OSD data. The ``data_vg`` key represents the volume group name that your
``data`` logical volume resides on. This key is required for purging of OSDs
created by this scenario.
.. note::
Any logical volume or logical group used in ``lvm_volumes`` must be a name and not a path.
.. note::
You can not use the same journal for many OSDs.
``filestore``
^^^^^^^^^^^^^
There is filestore support which can be enabled with:
.. code-block:: yaml
osd_objectstore: filestore
To configure this scenario use the ``lvm_volumes`` config option.
``lvm_volumes`` is a list of dictionaries which expects a volume name and
a volume group for logical volumes, but can also accept a parition in the case of
``filestore`` for the ``journal``.
The following keys are accepted for a ``filestore`` deployment:
* ``data``
* ``data_vg`` (not required if ``data`` is a raw device or partition)
* ``journal``
* ``journal_vg`` (not required if ``journal`` is a partition and not a logical volume)
* ``crush_device_class`` (optional, sets the crush device class for the OSD)
The ``journal`` key represents the logical volume name or partition that will be used for your OSD journal.
For example, a configuration to use the ``lvm`` osd scenario would look like:
.. code-block:: yaml
osd_objectstore: filestore
osd_scenario: lvm
lvm_volumes:
- data: data-lv1
data_vg: vg1
journal: journal-lv1
journal_vg: vg2
crush_device_class: foo
- data: data-lv2
journal: /dev/sda
data_vg: vg1
- data: data-lv3
journal: /dev/sdb1
data_vg: vg2
- data: /dev/sda
journal: /dev/sdb1
- data: /dev/sda1
journal: journal-lv1
journal_vg: vg2
For example, a configuration to use the ``lvm`` osd scenario with encryption would look like:
.. code-block:: yaml
osd_objectstore: filestore
osd_scenario: lvm
dmcrypt: True
lvm_volumes:
- data: data-lv1
data_vg: vg1
journal: journal-lv1
journal_vg: vg2
crush_device_class: foo
If you wished to use ``devices`` instead of ``lvm_volumes`` your configuration would look like:
.. code-block:: yaml
osd_objectstore: filestore
osd_scenario: lvm
crush_device_class: foo
devices:
- /dev/sda
- /dev/sdc
.. note::
If you wish to change set the ``crush_device_class`` for the OSDs when using ``devices`` you must set it
using the global ``crush_device_class`` option as shown above. There is no way to define a specific crush device
class per OSD when using ``devices`` like there is for ``lvm_volumes``.
``bluestore``
^^^^^^^^^^^^^
This scenario allows a combination of devices to be used in an OSD.
``bluestore`` can work just with a single "block" device (specified by the
``data`` and optionally ``data_vg``) or additionally with a ``block.wal`` and ``block.db``
(interchangeably)
The following keys are accepted for a ``bluestore`` deployment:
* ``data`` (required)
* ``data_vg`` (not required if ``data`` is a raw device or partition)
* ``db`` (optional for ``block.db``)
* ``db_vg`` (optional for ``block.db``)
* ``wal`` (optional for ``block.wal``)
* ``wal_vg`` (optional for ``block.wal``)
* ``crush_device_class`` (optional, sets the crush device class for the OSD)
A ``bluestore`` lvm deployment, for all four different combinations supported
could look like:
.. code-block:: yaml
osd_objectstore: bluestore
osd_scenario: lvm
lvm_volumes:
- data: data-lv1
data_vg: vg1
crush_device_class: foo
- data: data-lv2
data_vg: vg1
wal: wal-lv1
wal_vg: vg2
- data: data-lv3
data_vg: vg2
db: db-lv1
db_vg: vg2
- data: data-lv4
data_vg: vg4
db: db-lv4
db_vg: vg4
wal: wal-lv4
wal_vg: vg4
- data: /dev/sda
If you wished to use ``devices`` instead of ``lvm_volumes`` your configuration would look like:
.. code-block:: yaml
osd_objectstore: bluestore
osd_scenario: lvm
crush_device_class: foo
devices:
- /dev/sda
- /dev/sdc
.. note::
If you wish to change set the ``crush_device_class`` for the OSDs when using ``devices`` you must set it
using the global ``crush_device_class`` option as shown above. There is no way to define a specific crush device
class per OSD when using ``devices`` like there is for ``lvm_volumes``.