mirror of https://github.com/ceph/ceph
433 lines
9.2 KiB
ReStructuredText
433 lines
9.2 KiB
ReStructuredText
.. _drivegroups:
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=========================
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OSD Service Specification
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=========================
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:ref:`orchestrator-cli-service-spec` of type ``osd`` are a way to describe a cluster layout using the properties of disks.
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It gives the user an abstract way tell ceph which disks should turn into an OSD
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with which configuration without knowing the specifics of device names and paths.
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Instead of doing this
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.. prompt:: bash [monitor.1]#
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ceph orch daemon add osd *<host>*:*<path-to-device>*
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for each device and each host, we can define a yaml|json file that allows us to describe
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the layout. Here's the most basic example.
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Create a file called i.e. osd_spec.yml
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.. code-block:: yaml
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service_type: osd
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service_id: default_drive_group <- name of the drive_group (name can be custom)
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placement:
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host_pattern: '*' <- which hosts to target, currently only supports globs
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data_devices: <- the type of devices you are applying specs to
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all: true <- a filter, check below for a full list
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This would translate to:
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Turn any available(ceph-volume decides what 'available' is) into an OSD on all hosts that match
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the glob pattern '*'. (The glob pattern matches against the registered hosts from `host ls`)
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There will be a more detailed section on host_pattern down below.
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and pass it to `osd create` like so
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.. prompt:: bash [monitor.1]#
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ceph orch apply osd -i /path/to/osd_spec.yml
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This will go out on all the matching hosts and deploy these OSDs.
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Since we want to have more complex setups, there are more filters than just the 'all' filter.
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Also, there is a `--dry-run` flag that can be passed to the `apply osd` command, which gives you a synopsis
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of the proposed layout.
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Example
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.. prompt:: bash [monitor.1]#
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[monitor.1]# ceph orch apply osd -i /path/to/osd_spec.yml --dry-run
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Filters
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=======
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.. note::
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Filters are applied using a `AND` gate by default. This essentially means that a drive needs to fulfill all filter
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criteria in order to get selected.
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If you wish to change this behavior you can adjust this behavior by setting
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`filter_logic: OR` # valid arguments are `AND`, `OR`
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in the OSD Specification.
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You can assign disks to certain groups by their attributes using filters.
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The attributes are based off of ceph-volume's disk query. You can retrieve the information
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with
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.. code-block:: bash
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ceph-volume inventory </path/to/disk>
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Vendor or Model:
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-------------------
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You can target specific disks by their Vendor or by their Model
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.. code-block:: yaml
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model: disk_model_name
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or
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.. code-block:: yaml
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vendor: disk_vendor_name
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Size:
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--------------
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You can also match by disk `Size`.
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.. code-block:: yaml
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size: size_spec
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Size specs:
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___________
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Size specification of format can be of form:
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* LOW:HIGH
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* :HIGH
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* LOW:
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* EXACT
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Concrete examples:
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Includes disks of an exact size
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.. code-block:: yaml
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size: '10G'
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Includes disks which size is within the range
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.. code-block:: yaml
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size: '10G:40G'
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Includes disks less than or equal to 10G in size
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.. code-block:: yaml
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size: ':10G'
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Includes disks equal to or greater than 40G in size
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.. code-block:: yaml
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size: '40G:'
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Sizes don't have to be exclusively in Gigabyte(G).
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Supported units are Megabyte(M), Gigabyte(G) and Terrabyte(T). Also appending the (B) for byte is supported. MB, GB, TB
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Rotational:
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-----------
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This operates on the 'rotational' attribute of the disk.
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.. code-block:: yaml
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rotational: 0 | 1
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`1` to match all disks that are rotational
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`0` to match all disks that are non-rotational (SSD, NVME etc)
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All:
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------------
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This will take all disks that are 'available'
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Note: This is exclusive for the data_devices section.
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.. code-block:: yaml
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all: true
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Limiter:
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--------
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When you specified valid filters but want to limit the amount of matching disks you can use the 'limit' directive.
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.. code-block:: yaml
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limit: 2
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For example, if you used `vendor` to match all disks that are from `VendorA` but only want to use the first two
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you could use `limit`.
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.. code-block:: yaml
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data_devices:
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vendor: VendorA
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limit: 2
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Note: Be aware that `limit` is really just a last resort and shouldn't be used if it can be avoided.
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Additional Options
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===================
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There are multiple optional settings you can use to change the way OSDs are deployed.
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You can add these options to the base level of a DriveGroup for it to take effect.
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This example would deploy all OSDs with encryption enabled.
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.. code-block:: yaml
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service_type: osd
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service_id: example_osd_spec
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placement:
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host_pattern: '*'
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data_devices:
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all: true
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encrypted: true
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See a full list in the DriveGroupSpecs
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.. py:currentmodule:: ceph.deployment.drive_group
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.. autoclass:: DriveGroupSpec
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:members:
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:exclude-members: from_json
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Examples
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========
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The simple case
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---------------
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All nodes with the same setup
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.. code-block:: none
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20 HDDs
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Vendor: VendorA
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Model: HDD-123-foo
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Size: 4TB
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2 SSDs
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Vendor: VendorB
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Model: MC-55-44-ZX
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Size: 512GB
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This is a common setup and can be described quite easily:
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_default
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placement:
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host_pattern: '*'
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data_devices:
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model: HDD-123-foo <- note that HDD-123 would also be valid
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db_devices:
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model: MC-55-44-XZ <- same here, MC-55-44 is valid
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However, we can improve it by reducing the filters on core properties of the drives:
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_default
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placement:
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host_pattern: '*'
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data_devices:
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rotational: 1
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db_devices:
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rotational: 0
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Now, we enforce all rotating devices to be declared as 'data devices' and all non-rotating devices will be used as shared_devices (wal, db)
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If you know that drives with more than 2TB will always be the slower data devices, you can also filter by size:
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_default
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placement:
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host_pattern: '*'
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data_devices:
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size: '2TB:'
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db_devices:
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size: ':2TB'
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Note: All of the above DriveGroups are equally valid. Which of those you want to use depends on taste and on how much you expect your node layout to change.
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The advanced case
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-----------------
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Here we have two distinct setups
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.. code-block:: none
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20 HDDs
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Vendor: VendorA
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Model: HDD-123-foo
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Size: 4TB
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12 SSDs
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Vendor: VendorB
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Model: MC-55-44-ZX
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Size: 512GB
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2 NVMEs
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Vendor: VendorC
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Model: NVME-QQQQ-987
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Size: 256GB
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* 20 HDDs should share 2 SSDs
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* 10 SSDs should share 2 NVMes
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This can be described with two layouts.
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_hdd
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placement:
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host_pattern: '*'
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data_devices:
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rotational: 0
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db_devices:
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model: MC-55-44-XZ
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limit: 2 (db_slots is actually to be favoured here, but it's not implemented yet)
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---
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service_type: osd
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service_id: osd_spec_ssd
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placement:
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host_pattern: '*'
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data_devices:
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model: MC-55-44-XZ
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db_devices:
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vendor: VendorC
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This would create the desired layout by using all HDDs as data_devices with two SSD assigned as dedicated db/wal devices.
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The remaining SSDs(8) will be data_devices that have the 'VendorC' NVMEs assigned as dedicated db/wal devices.
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The advanced case (with non-uniform nodes)
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------------------------------------------
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The examples above assumed that all nodes have the same drives. That's however not always the case.
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Node1-5
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.. code-block:: none
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20 HDDs
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Vendor: Intel
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Model: SSD-123-foo
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Size: 4TB
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2 SSDs
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Vendor: VendorA
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Model: MC-55-44-ZX
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Size: 512GB
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Node6-10
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.. code-block:: none
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5 NVMEs
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Vendor: Intel
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Model: SSD-123-foo
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Size: 4TB
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20 SSDs
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Vendor: VendorA
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Model: MC-55-44-ZX
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Size: 512GB
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You can use the 'host_pattern' key in the layout to target certain nodes. Salt target notation helps to keep things easy.
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_node_one_to_five
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placement:
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host_pattern: 'node[1-5]'
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data_devices:
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rotational: 1
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db_devices:
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rotational: 0
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---
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service_type: osd
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service_id: osd_spec_six_to_ten
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placement:
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host_pattern: 'node[6-10]'
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data_devices:
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model: MC-55-44-XZ
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db_devices:
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model: SSD-123-foo
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This applies different OSD specs to different hosts depending on the `host_pattern` key.
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Dedicated wal + db
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------------------
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All previous cases co-located the WALs with the DBs.
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It's however possible to deploy the WAL on a dedicated device as well, if it makes sense.
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.. code-block:: none
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20 HDDs
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Vendor: VendorA
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Model: SSD-123-foo
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Size: 4TB
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2 SSDs
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Vendor: VendorB
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Model: MC-55-44-ZX
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Size: 512GB
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2 NVMEs
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Vendor: VendorC
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Model: NVME-QQQQ-987
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Size: 256GB
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The OSD spec for this case would look like the following (using the `model` filter):
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.. code-block:: yaml
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service_type: osd
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service_id: osd_spec_default
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placement:
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host_pattern: '*'
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data_devices:
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model: MC-55-44-XZ
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db_devices:
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model: SSD-123-foo
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wal_devices:
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model: NVME-QQQQ-987
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This can easily be done with other filters, like `size` or `vendor` as well.
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