Documentation on cache tier setup for ceph
Additionally add some stuff in there for erasure coding Change-Id: I3bbfa3d2cbf6f8e38f517d05f6f0509abeb3c8f1 Closes-Bug: #1512535
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Sam Yaple
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Ceph in Kolla
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=============
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The out-of-the-box Ceph deployment requires 3 hosts with at least one block
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device on each host that can be dedicated for sole use by Ceph. However, with
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tweaks to the Ceph cluster you can deploy a "healthy" cluster with a single
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host and a single block device.
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Requirements
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------------
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Using Ceph requires at least two physical disks across the OpenStack deployment to operate correctly.
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* A minimum of 3 hosts for a vanilla deploy
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* A minimum of 1 block device per host
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Preparation and Deployment
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--------------------------
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For the disks used for Ceph, execute the following operations:
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To prepare a disk for use as a
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`Ceph OSD <http://docs.ceph.com/docs/master/man/8/ceph-osd/>`_ you must add a
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special partition label to the disk. This partition label is how Kolla detects
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the disks to format and bootstrap. Any disk with a matching parition label will
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be reformatted so use caution.
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To prepare an OSD as a storage drive, execute the following operations:
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::
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<WARNING ALL DATA ON $DISK will be LOST!>
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# <WARNING ALL DATA ON $DISK will be LOST!>
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# where $DISK is /dev/sdb or something similar
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parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP 1 -1
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where $DISK == /dev/sdb or something similar
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The following shows an example of using parted to configure /dev/sdb for usage with Kolla.
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@ -32,80 +43,87 @@ The following shows an example of using parted to configure /dev/sdb for usage w
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1 1049kB 10.7GB 10.7GB KOLLA_CEPH_OSD_BOOTSTRAP
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Edit the [storage] group in the inventory which contains the hostname(or IP) of the Ceph-OSD hosts
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which have the above disks. Note: ssh authentication is required for Ceph, even in all-in-one.
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(TODO(CBR09): insert link to bug around this if there is one). The following shows an example
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of two Ceph-OSD hosts which using one disk of the controller node and one disk of compute1.
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Edit the [storage] group in the inventory which contains the hostname of the
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hosts that have the block devices you have prepped as shown above.
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::
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file: ansible/inventory/multinode
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...
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[storage]
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controller
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compute1
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...
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For AIO:
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Enable Ceph in /etc/kolla/globals.yml:
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::
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file: ansible/inventory/multinode
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...
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[storage]
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all-in-one
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...
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Enable Ceph in /etc/kolla/globals.yml (Ceph is disabled by default):
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::
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file: /etc/kolla/globals.yml
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....
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enable_ceph: "yes"
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....
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Finally deploy the Ceph-enabled OpenStack:
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::
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tools/kolla-ansible deploy -i ansible/inventory/multinode
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kolla-ansible deploy -i path/to/inventory
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Debugging Ceph
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--------------
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If Ceph is run in an all-in-one deployment or with less than three storage nodes, further
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configuration is required. It is necessary to change the default number of copies for the pool.
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The following example demonstrates how to change the number of copies for the pool:
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Using a Cache Tier
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------------------
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If the deployment includes two Ceph-OSD hosts as mentioned above, set the pool to 2.
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An optional
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`cache tier <http://docs.ceph.com/docs/hammer/rados/operations/cache-tiering/>`_
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can be deployed by formating at least one cache device and enabling cache
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tiering in the globals.yml configuration file.
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To prepare an OSD as a cache device, execute the following operations:
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::
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docker exec ceph_mon ceph osd pool set rbd size 2 (default only have rdb pool)
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# <WARNING ALL DATA ON $DISK will be LOST!>
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# where $DISK is /dev/sdb or something similar
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parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_CACHE_BOOTSTRAP 1 -1
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For AIO:
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Enable the Ceph cache tier in /etc/kolla/globals.yml:
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::
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docker exec ceph_mon ceph osd pool set rbd size 1 (default only have rdb pool)
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enable_ceph: "yes"
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ceph_enable_cache: "yes"
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# Valid options are [ forward, none, writeback ]
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ceph_cache_mode: "writeback"
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If Glance, Nova, and cinder have been deployed, all pools have to be modified.
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An example of modifying the pools:
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After this run the playbooks as you normally would. For example:
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::
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for p in images vms volumes backups rbd; do docker exec ceph_mon ceph osd pool set $p size 2; done
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kolla-ansible deploy -i path/to/inventory
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For AIO:
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Setting up an Erasure Coded Pool
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--------------------------------
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`Erasure code <http://docs.ceph.com/docs/hammer/rados/operations/erasure-code/>`_
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is the new big thing from Ceph. Kolla has the ability to setup your Ceph pools
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as erasure coded pools. Due to technical limitations with Ceph, using erasure
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coded pools as OpenStack uses them requires a cache tier. Additionally, you must
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make the choice to use an erasure coded pool or a replicated pool (the default)
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when you initially deploy. You cannot change this without completely removing
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the pool and recreating it.
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To enable erasure coded pools add the following options to your
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/etc/kolla/globals.yml configuration file:
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::
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for p in images vms volumes backups rbd; do docker exec ceph_mon ceph osd pool set $p size 1; done
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# A requirement for using the erasure-coded pools is you must setup a cache tier
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# Valid options are [ erasure, replicated ]
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ceph_pool_type: "erasure"
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# Optionally, you can change the profile
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#ceph_erasure_profile: "k=4 m=2 ruleset-failure-domain=host"
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After making this change, it is mandatory to restart all Ceph osd containers.
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Managing Ceph
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-------------
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Check the Ceph status for more diagnostic information. The sample output below
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indicates a healthy cluster:
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@ -121,3 +139,30 @@ indicates a healthy cluster:
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pgmap v27: 64 pgs, 1 pools, 0 bytes data, 0 objects
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68676 kB used, 20390 MB / 20457 MB avail
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64 active+clean
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If Ceph is run in an all-in-one deployment or with less than three storage nodes, further
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configuration is required. It is necessary to change the default number of copies for the pool.
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The following example demonstrates how to change the number of copies for the pool to 1:
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::
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docker exec ceph_mon ceph osd pool set rbd size 1
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If Glance, Nova, and cinder have been deployed, all pools have to be modified.
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An example of modifying the pools to have 2 copies:
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::
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for p in images vms volumes backups; do docker exec ceph_mon ceph osd pool set ${p} size 2; done
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If using a cache tier, these changes must be made as well:
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::
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for p in images vms volumes backups; do docker exec ceph_mon ceph osd pool set ${p}-cache size 2; done
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The default pool Ceph creates is named 'rbd'. It is safe to remove this pool:
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::
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docker exec ceph_mon ceph osd pool delete rbd rbd --yes-i-really-really-mean-it
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