.. _ceph-guide: =============================== Ceph - Software Defined Storage =============================== .. note:: The out-of-the-box Ceph deployment requires 3 hosts with at least one block device on each host that can be dedicated for sole use by Ceph. However, with tweaks to the Ceph cluster you can deploy a **healthy** cluster with a single host and a single block device. Requirements ------------ * A minimum of 3 hosts for a vanilla deploy * A minimum of 1 block device per host Preparation ----------- To prepare a disk for use as a `Ceph OSD `_ you must add a special partition label to the disk. This partition label is how Kolla detects the disks to format and bootstrap. Any disk with a matching partition label will be reformatted so use caution. Filestore ~~~~~~~~~ .. note:: From Rocky release - kolla-ansible by default creates Bluestore OSDs. Please see Configuration section to change that behaviour. To prepare a filestore OSD as a storage drive, execute the following operations: .. warning:: ALL DATA ON $DISK will be LOST! Where $DISK is /dev/sdb or something similar. .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP 1 -1 The following shows an example of using parted to configure ``/dev/sdb`` for usage with Kolla. .. code-block:: console parted /dev/sdb -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP 1 -1 parted /dev/sdb print Model: VMware, VMware Virtual S (scsi) Disk /dev/sdb: 10.7GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 10.7GB 10.7GB KOLLA_CEPH_OSD_BOOTSTRAP Bluestore ~~~~~~~~~ To prepare a bluestore OSD partition, execute the following operations: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_BS 1 -1 If only one device is offered, Kolla Ceph will create the bluestore OSD on the device. Kolla Ceph will create two partitions for OSD and block separately. If more than one devices are offered for one bluestore OSD, Kolla Ceph will create partitions for block, block.wal and block.db according to the partition labels. To prepare a bluestore OSD block partition, execute the following operations: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_BS_FOO_B 1 -1 To prepare a bluestore OSD block.wal partition, execute the following operations: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_BS_FOO_W 1 -1 To prepare a bluestore OSD block.db partition, execute the following operations: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_BS_FOO_D 1 -1 Kolla Ceph will handle the bluestore OSD according to the above up to four partition labels. In Ceph bluestore OSD, the block.wal and block.db partitions are not mandatory. .. note:: In the case there are more than one devices in one bluestore OSD and there are more than one bluestore OSD in one node, it is required to use suffixes (``_42``, ``_FOO``, ``_FOO42``, ..). Kolla Ceph will gather all the partition labels and deploy bluestore OSD on top of the devices which have the same suffix in the partition label. Using an external journal drive ------------------------------- .. note:: The section is only meaningful for Ceph filestore OSD. The steps documented above created a journal partition of 5 GByte and a data partition with the remaining storage capacity on the same tagged drive. It is a common practice to place the journal of an OSD on a separate journal drive. This section documents how to use an external journal drive. Prepare the storage drive in the same way as documented above: .. warning:: ALL DATA ON $DISK will be LOST! Where $DISK is /dev/sdb or something similar. .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_FOO 1 -1 To prepare the journal external drive execute the following command: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_FOO_J 1 -1 .. note:: Use different suffixes (``_42``, ``_FOO``, ``_FOO42``, ..) to use different external journal drives for different storage drives. One external journal drive can only be used for one storage drive. .. note:: The partition labels ``KOLLA_CEPH_OSD_BOOTSTRAP`` and ``KOLLA_CEPH_OSD_BOOTSTRAP_J`` are not working when using external journal drives. It is required to use suffixes (``_42``, ``_FOO``, ``_FOO42``, ..). If you want to setup only one storage drive with one external journal drive it is also necessary to use a suffix. Configuration ------------- Edit the ``[storage]`` group in the inventory which contains the hostname of the hosts that have the block devices you have prepped as shown above. .. code-block:: ini [storage] controller compute1 Enable Ceph in ``/etc/kolla/globals.yml``: .. code-block:: yaml enable_ceph: "yes" RadosGW is optional, enable it in ``/etc/kolla/globals.yml``: .. code-block:: yaml enable_ceph_rgw: "yes" .. note:: By default RadosGW supports both Swift and S3 API, and it is not completely compatible with Swift API. The option `ceph_rgw_compatibility` in ``ansible/group_vars/all.yml`` can enable/disable the RadosGW compatibility with Swift API completely. After changing the value, run the "reconfigure“ command to enable. Configure the Ceph store type in ``ansible/group_vars/all.yml``, the default value is ``bluestore`` in Rocky: .. code-block:: yaml ceph_osd_store_type: "bluestore" .. note:: Regarding number of placement groups (PGs) Kolla sets very conservative values for the number of PGs per pool (`ceph_pool_pg_num` and `ceph_pool_pgp_num`). This is in order to ensure the majority of users will be able to deploy Ceph out of the box. It is *highly* recommended to consult the official Ceph documentation regarding these values before running Ceph in any kind of production scenario. RGW requires a healthy cluster in order to be successfully deployed. On initial start up, RGW will create several pools. The first pool should be in an operational state to proceed with the second one, and so on. So, in the case of an **all-in-one** deployment, it is necessary to change the default number of copies for the pools before deployment. Modify the file ``/etc/kolla/config/ceph.conf`` and add the contents: .. path /etc/kolla/config/ceph.conf .. code-block:: ini [global] osd pool default size = 1 osd pool default min size = 1 To build a high performance and secure Ceph Storage Cluster, the Ceph community recommend the use of two separate networks: public network and cluster network. Edit the ``/etc/kolla/globals.yml`` and configure the ``cluster_interface``: .. path /etc/kolla/globals.yml .. code-block:: yaml cluster_interface: "eth2" For more details, see `NETWORK CONFIGURATION REFERENCE `_ of Ceph Documentation. Deployment ---------- Finally deploy the Ceph-enabled OpenStack: .. code-block:: console kolla-ansible deploy -i path/to/inventory .. note:: Kolla Ceph supports mixed Ceph OSD deployment, i.e. some Ceph OSDs are bluestore, the others are filestore. The ``ceph_osd_store_type`` of each Ceph OSD can be configured under ``[storage]`` in the multinode inventory file. The Ceph OSD store type is unique in one storage node. For example: .. code-block:: ini [storage] storage_node1_hostname ceph_osd_store_type=bluestore storage_node2_hostname ceph_osd_store_type=bluestore storage_node3_hostname ceph_osd_store_type=filestore storage_node4_hostname ceph_osd_store_type=filestore Using Cache Tiering ------------------- An optional `cache tiering `_ can be deployed by formatting at least one cache device and enabling cache. tiering in the globals.yml configuration file. To prepare a filestore OSD as a cache device, execute the following operations: .. code-block:: console parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_CACHE_BOOTSTRAP 1 -1 .. note:: To prepare a bluestore OSD as a cache device, change the partition name in the above command to "KOLLA_CEPH_OSD_CACHE_BOOTSTRAP_BS". The deployment of bluestore cache OSD is the same as bluestore OSD. Enable the Ceph cache tier in ``/etc/kolla/globals.yml``: .. code-block:: yaml enable_ceph: "yes" ceph_enable_cache: "yes" # Valid options are [ forward, none, writeback ] ceph_cache_mode: "writeback" After this run the playbooks as you normally would, for example: .. code-block:: console kolla-ansible deploy -i path/to/inventory Setting up an Erasure Coded Pool -------------------------------- `Erasure code `_ is the new big thing from Ceph. Kolla has the ability to setup your Ceph pools as erasure coded pools. Due to technical limitations with Ceph, using erasure coded pools as OpenStack uses them requires a cache tier. Additionally, you must make the choice to use an erasure coded pool or a replicated pool (the default) when you initially deploy. You cannot change this without completely removing the pool and recreating it. To enable erasure coded pools add the following options to your ``/etc/kolla/globals.yml`` configuration file: .. code-block:: yaml # A requirement for using the erasure-coded pools is you must setup a cache tier # Valid options are [ erasure, replicated ] ceph_pool_type: "erasure" # Optionally, you can change the profile #ceph_erasure_profile: "k=4 m=2 ruleset-failure-domain=host" Managing Ceph ------------- Check the Ceph status for more diagnostic information. The sample output below indicates a healthy cluster: .. code-block:: console docker exec ceph_mon ceph -s cluster: id: f2ed6c00-c043-4e1c-81b6-07c512db26b1 health: HEALTH_OK services: mon: 1 daemons, quorum 172.16.31.121 mgr: poc12-01(active) osd: 4 osds: 4 up, 4 in; 5 remapped pgs data: pools: 4 pools, 512 pgs objects: 0 objects, 0 bytes usage: 432 MB used, 60963 MB / 61395 MB avail pgs: 512 active+clean If Ceph is run in an **all-in-one** deployment or with less than three storage nodes, further configuration is required. It is necessary to change the default number of copies for the pool. The following example demonstrates how to change the number of copies for the pool to 1: .. code-block:: console docker exec ceph_mon ceph osd pool set rbd size 1 All the pools must be modified if Glance, Nova, and Cinder have been deployed. An example of modifying the pools to have 2 copies: .. code-block:: console for p in images vms volumes backups; do docker exec ceph_mon ceph osd pool set ${p} size 2; done If using a cache tier, these changes must be made as well: .. code-block:: console for p in images vms volumes backups; do docker exec ceph_mon ceph osd pool set ${p}-cache size 2; done The default pool Ceph creates is named **rbd**. It is safe to remove this pool: .. code-block:: console docker exec ceph_mon ceph osd pool delete rbd rbd --yes-i-really-really-mean-it Troubleshooting --------------- Deploy fails with 'Fetching Ceph keyrings ... No JSON object could be decoded' ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If an initial deploy of Ceph fails, perhaps due to improper configuration or similar, the cluster will be partially formed and will need to be reset for a successful deploy. In order to do this the operator should remove the `ceph_mon_config` volume from each Ceph monitor node: .. code-block:: console ansible -i ansible/inventory/multinode \ -a 'docker volume rm ceph_mon_config' \ ceph-mon Simple 3 Node Example --------------------- This example will show how to deploy Ceph in a very simple setup using 3 storage nodes. 2 of those nodes (kolla1 and kolla2) will also provide other services like control, network, compute, and monitoring. The 3rd (kolla3) node will only act as a storage node. This example will only focus on the Ceph aspect of the deployment and assumes that you can already deploy a fully functional environment using 2 nodes that does not employ Ceph yet. So we will be adding to the existing multinode inventory file you already have. Each of the 3 nodes are assumed to have two disk, ``/dev/sda`` (40GB) and ``/dev/sdb`` (10GB). Size is not all that important... but for now make sure each sdb disk are of the same size and are at least 10GB. This example will use a single disk (/dev/sdb) for both Ceph data and journal. It will not implement caching. Here is the top part of the multinode inventory file used in the example environment before adding the 3rd node for Ceph: .. code-block:: ini [control] # These hostname must be resolvable from your deployment host kolla1.ducourrier.com kolla2.ducourrier.com [network] kolla1.ducourrier.com kolla2.ducourrier.com [compute] kolla1.ducourrier.com kolla2.ducourrier.com [monitoring] kolla1.ducourrier.com kolla2.ducourrier.com [storage] kolla1.ducourrier.com kolla2.ducourrier.com Configuration ~~~~~~~~~~~~~ To prepare the 2nd disk (/dev/sdb) of each nodes for use by Ceph you will need to add a partition label to it as shown below: .. code-block:: console parted /dev/sdb -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP 1 -1 Make sure to run this command on each of the 3 nodes or the deployment will fail. Next, edit the multinode inventory file and make sure the 3 nodes are listed under ``[storage]``. In this example I will add kolla3.ducourrier.com to the existing inventory file: .. code-block:: ini [control] # These hostname must be resolvable from your deployment host kolla1.ducourrier.com kolla2.ducourrier.com [network] kolla1.ducourrier.com kolla2.ducourrier.com [compute] kolla1.ducourrier.com kolla2.ducourrier.com [monitoring] kolla1.ducourrier.com kolla2.ducourrier.com [storage] kolla1.ducourrier.com kolla2.ducourrier.com kolla3.ducourrier.com It is now time to enable Ceph in the environment by editing the ``/etc/kolla/globals.yml`` file: .. code-block:: yaml enable_ceph: "yes" enable_ceph_rgw: "yes" enable_cinder: "yes" glance_backend_file: "no" glance_backend_ceph: "yes" Deployment ~~~~~~~~~~ Finally deploy the Ceph-enabled configuration: .. code-block:: console kolla-ansible deploy -i path/to/inventory-file