Deploying Ceph with cephadm¶
TripleO can deploy and configure Ceph as if it was a composable OpenStack service and configure OpenStack services like Nova, Glance, Cinder, and Cinder Backup to use its RBD interface as a storage backend as well as configure Ceph’s RGW service as the backend for OpenStack object storage. Both Ceph and OpenStack containers can also run “hyperconverged” on the same container host.
This guide assumes that the undercloud is already installed and ready to deploy an overcloud as described in TripleO OpenStack Deployment.
Limitations¶
TripleO deployments of Ceph with cephadm are only supported in Wallaby or newer. The default version of Ceph deployed by TripleO in Wallaby is Pacific, regardless of if cephadm or ceph-ansible is used to deploy it.
TripleO can only deploy one Ceph cluster in the overcloud per Heat stack. However, within that Heat stack it’s possible to configure an overcloud to communicate with multiple Ceph clusters which are external to the overcloud. To do this, follow this document to configure the “internal” Ceph cluster which is part of the overcloud and also use the CephExternalMultiConfig parameter described in the Use an external Ceph cluster with the Overcloud documentation.
Prerequisite: Ensure the Ceph container is available¶
Before deploying Ceph follow the Container Image Preparation documentation so the appropriate Ceph container image is used. The output of the openstack tripleo container image prepare command should contain a line like the following:
ContainerCephDaemonImage: undercloud.ctlplane.mydomain.tld:8787/ceph-ci/daemon:v6.0.0-stable-6.0-pacific-centos-8-x86_64
Prerequisite: Ensure the cephadm package is installed¶
The cephadm package needs to be installed on at least one node in the overcloud in order to bootstrap the first node of the Ceph cluster.
The cephadm package is pre-built into the overcloud-full image. The tripleo_cephadm role will also use Ansible’s package module to ensure it is present. If tripleo-repos is passed the ceph argument for Wallaby or newer, then the CentOS SIG Ceph repository will be enabled with the appropriate version containing the cephadm package, e.g. for Wallaby the ceph-pacific repository is enabled.
Prerequisite: Ensure Disks are Clean¶
cephadm does not reformat the OSD disks and expect them to be clean to complete successfully. Consequently, when reusing the same nodes (or disks) for new deployments, it is necessary to clean the disks before every new attempt. One option is to enable the automated cleanup functionality in Ironic, which will zap the disks every time that a node is released. The same process can be executed manually or only for some target nodes, see cleaning instructions in the Ironic documentation.
Deploying Ceph During Overcloud Deployment¶
To deploy an overcloud with a Ceph include the appropriate environment file as in the example below:
openstack overcloud deploy --templates \
-e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml
If you only wish to deploy Ceph RBD without RGW then use the following variation of the above:
openstack overcloud deploy --templates \
-e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm-rbd-only.yaml
Do not directly edit the environments/cephadm/cephadm.yaml or cephadm-rbd-only.yaml file. If you wish to override the defaults, as described below in the sections starting with “Overriding”, then place those overrides in a separate cephadm-overrides.yaml file and deploy like this:
openstack overcloud deploy --templates \
-e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml \
-e cephadm-overrides.yaml
Deploying with the commands above will result in the processes described in the rest of this document.
Deploying Ceph Before Overcloud Deployment¶
In Wallaby and newer it is possible to provision hardware and deploy Ceph before deploying the overcloud on the same hardware. This feature is called “deployed ceph” and it uses the command openstack overcloud ceph deploy which executes the same Ansible roles described below. For more details see Deployed Ceph.
Overview of Ceph Deployment with TripleO and cephadm¶
When Ceph is deployed during overcloud configuration or when Ceph is deployed before overcloud configuration with Deployed Ceph, TripleO will use Ansible automate the process described in the cephadm documentation to bootstrap a new cluster. It will bootstrap a single Ceph monitor and manager on one server (by default on the first Controller node) and then add the remaining servers to the cluster by using Ceph orchestrator to apply a Ceph Service Specification. The Ceph Service Specification is generated automatically based on TripleO composable roles and most of the existing THT parameters remain backwards compatible. During stack updates the same bootstrap process is not executed.
Details of Ceph Deployment with TripleO and cephadm¶
After the hardware is provisioned, the user ceph-admin is created on the overcloud nodes. The ceph-admin user has one set of public and private SSH keys created on the undercloud (in /home/stack/.ssh/ceph-admin-id_rsa.pub and .ssh/ceph-admin-id_rsa) which is distributed to all overcloud nodes which host the Ceph Mgr and Mon service; only the public key is distributed to nodes in the Ceph cluster which do not run the Mgr or Mon service. Unlike the tripleo-admin user, this allows the ceph-admin user to SSH from any overcloud node hosting the Mon or Mgr service to any other overcloud node hosting the Mon or Mgr service. By default these services run on the controller nodes so this means by default that Controllers can SSH to each other but other nodes, e.g. CephStorage nodes, cannot SSH to Controller nodes. cephadm requires this type of access in order to scale from more than one Ceph node.
The deployment definition as described TripleO Heat Templates, e.g. which servers run which services according to composable roles, will be converted by the tripleo-ansible ceph_spec_bootstrap module into a Ceph Service Specification file. The module has the ability to do this based on the Ansible inventory generated by the tripleo-ansible-inventory. When Ceph is deployed during overcloud configuration by including the cephadm.yaml environment file, the module uses the Ansible inventory to create the Ceph Service Specification. In this scenario the default location of the generated Ceph Service Specification file is config-download/<STACK>/cephadm/ceph_spec.yaml.
The same ceph_spec_bootstrap module can also generate the Ceph Service Specification file from a combination of a TripleO roles data file (e.g. /usr/share/openstack-tripleo-heat-templates/roles_data.yaml) and the output of the command openstack overcloud node provision –output deployed_metal.yaml. When Ceph is deployed before overcloud configuration as described in Deployed Ceph, the module uses the deployed_metal.yaml and roles_data.yaml to create the Ceph Service Specification.
After the ceph-admin user is created, ceph_spec.yaml is copied to the bootstrap host. The bootstrap host will be the first host in the ceph_mons group of the inventory generated by the tripleo-ansible-inventory command. By default this is the first controller node.
Ansible will then interact only with the bootstrap host. It will run the cephadm commands necessary to bootstrap a small Ceph cluster on the bootstrap node and then run ceph orch apply -i ceph_spec.yaml and cephadm will use the ceph-admin account and SSH keys to add the other nodes.
After the full Ceph cluster is running, either as a result of Deployed Ceph or by cephadm being triggered during the overcloud deployment via the cephadm.yaml environment file, the Ceph pools and the cephx keys to access the pools will be created as defined or overridden as described in the Heat environment examples below. The information necessary to configure Ceph clients will then be extracted to /home/stack/ceph_client.yml on the undercloud and passed to the as input to the tripleo-ansible role tripleo_ceph_client which will then configure the rest of the overcloud to use the new Ceph cluster as described in the Use an external Ceph cluster with the Overcloud documentation.
When openstack overcloud deploy is re-run in order to update the stack, the cephadm bootstrap process is not repeated because that process is only run if cephadm list returns an empty list. Thus, configuration changes to the running Ceph cluster, outside of scale up as described below, should be made directly with Ceph Orchestrator.
Overriding Ceph Configuration Options during deployment¶
To override the keys and values of the Ceph configuration database, which has been traditionally stored in the Ceph configuration file, e.g. /etc/ceph/ceph.conf, use the CephConfigOverrides parameter. For example, if the cephadm-overrides.yaml file referenced in the example openstack overcloud deploy command in the previous section looked like the following:
parameter_defaults:
CephConfigOverrides:
mon:
mon_warn_on_pool_no_redundancy: false
Then the Ceph monitors would be configured with the above parameter and a command like the following could confirm it:
[stack@standalone ~]$ sudo cephadm shell -- ceph config dump | grep warn
Inferring fsid 65e8d744-eaec-4ff1-97be-2551d452426d
Inferring config /var/lib/ceph/65e8d744-eaec-4ff1-97be-2551d452426d/mon.standalone.localdomain/config
Using recent ceph image quay.ceph.io/ceph-ci/daemon@sha256:6b3c720e58ae84b502bd929d808ba63a1e9b91f710418be9df3ee566227546c0
mon advanced mon_warn_on_pool_no_redundancy false
[stack@standalone ~]$
In the above example the configuration group is ‘mon’ for the Ceph monitor. The supported configuration groups are ‘global’, ‘mon’, ‘mgr’, ‘osd’, ‘mds’, and ‘client’. If no group is provided, then the default configuration group is ‘global’.
The above does not apply to Deployed Ceph.
Overriding Server Configuration after deployment¶
To make a Ceph server configuration change, after the cluster has been deployed, use the ceph config command. A ‘/etc/ceph/ceph.conf’ file is not distributed to all Ceph servers and instead Ceph’s centralized configuration management is used.
A single ‘/etc/ceph/ceph.conf’ file may be found on the bootstrap node. The directives under CephConfigOverrides are used to create a config file, e.g. assimilate_ceph.conf, which is passed to cephadm bootstrap with –config assimilate_ceph.conf so that those directives are applied to the new cluster at bootstrap. The option –output-config /etc/ceph/ceph.conf is also passed to the cephadm bootstrap command and that’s what creates the ceph.conf on the bootstrap node. The name of the file is ceph.conf because the CephClusterName parameter defaults to “ceph”. If CephClusterName was set to “foo”, then the file would be called /etc/ceph/foo.conf.
By default the parameters in CephConfigOverrides are only applied to a new Ceph server at bootstrap. They are ignored during stack updates because ApplyCephConfigOverridesOnUpdate defaults to false. When ApplyCephConfigOverridesOnUpdate is set to true, parameters in CephConfigOverrides are put into a file, e.g. assimilate_ceph.conf, and a command like ceph config assimilate-conf -i assimilate_ceph.conf is run.
When using Deployed Ceph the openstack overcloud ceph deploy command outputs an environment file with ApplyCephConfigOverridesOnUpdate set to true so that services not covered by deployed ceph, e.g. RGW, can have the configuration changes that they need applied during overcloud deployment. After the deployed ceph process has run and then after the overcloud is deployed, it is recommended to set ApplyCephConfigOverridesOnUpdate to false.
Overriding Client Configuration after deployment¶
To make a Ceph client configuration change, update the parameters in CephConfigOverrides and run a stack update. This will not change the configuration for the Ceph servers unless ApplyCephConfigOverridesOnUpdate is set to true (as described in the section above). By default it should only change configurations for the Ceph clients. Examples of Ceph clients include Nova compute containers, Cinder volume containers, Glance image containers, etc.
The CephConfigOverrides directive updates all Ceph client configuration files on the overcloud in the CephConfigPath (which defaults to /var/lib/tripleo-config/ceph). The CephConfigPath is mounted on the client containers as /etc/ceph. The name of the configuration file is ceph.conf because the CephClusterName parameter defaults to “ceph”. If CephClusterName was set to “foo”, then the file would be called /etc/ceph/foo.conf.
Overriding the Ceph Service Specification¶
All TripleO cephadm deployments rely on a valid Ceph Service Specification. It is not necessary to provide a service specification directly as TripleO will generate one dynamically. However, one may provide their own service specification by disabling the dynamic spec generation and providing a path to their service specification as shown in the following:
parameter_defaults:
CephDynamicSpec: false
CephSpecPath: /home/stack/cephadm_spec.yaml
The CephDynamicSpec parameter defaults to true. The CephSpecPath defaults to “{{ playbook_dir }}/cephadm/ceph_spec.yaml”, where the value of “{{ playbook_dir }}” is controlled by config-download. If CephDynamicSpec is true and CephSpecPath is set to a valid path, then the spec will be created at that path before it is used to deploy Ceph.
The CephDynamicSpec and CephSpecPath parameters are not available when using “deployed ceph”, but the functionality is available via the –ceph-spec command line option as described in Deployed Ceph.
Overriding which disks should be OSDs¶
The Advanced OSD Service Specifications should be used to define how disks are used as OSDs.
By default all available disks (excluding the disk where the operating system is installed) are used as OSDs. This is because the CephOsdSpec parameter defaults to the following:
data_devices:
all: true
In the above example, the data_devices key is valid for any Ceph Service Specification whose service_type is “osd”. Other OSD service types, as found in the Advanced OSD Service Specifications, may be set by overriding the CephOsdSpec parameter. In the example below all rotating devices will be data devices and all non-rotating devices will be used as shared devices (wal, db) following:
parameter_defaults:
CephOsdSpec:
data_devices:
rotational: 1
db_devices:
rotational: 0
When the dynamic Ceph service specification is built (whenever CephDynamicSpec is true) whatever is in the CephOsdSpec will be appended to that section of the specification if the service_type is “osd”.
If CephDynamicSpec is false, then the OSD definition can also be placed directly in the Ceph Service Specification located at the path defined by CephSpecPath as described in the previous section.
The Provisioning of node-specific Hieradata feature is not supported by the cephadm integration but the Advanced OSD Service Specifications has a host_pattern parameter which specifies which host to target for certain data_devices definitions, so the equivalent functionality is available but with the new syntax. When using this option consider setting CephDynamicSpec to false and defining a custom specification which is passed to TripleO by setting the CephSpecPath.
The CephOsdSpec parameter is not available when using “deployed ceph”, but the same functionality is available via –osd-spec command line option as described in Deployed Ceph.
Overriding Ceph Pools and Placement Group values during deployment¶
The default cephadm deployment as triggered by TripleO has Autoscaling Placement Groups enabled. Thus, it is not necessary to use pgcalc and hard code a PG number per pool.
However, the interfaces described in the Configuring Ceph with Custom Config Settings (via ceph-ansible or puppet-ceph) for configuring the placement groups per pool remain backwards compatible. For example, to set the default pool size and default PG number per pool use an example like the following:
parameter_defaults:
CephPoolDefaultSize: 3
CephPoolDefaultPgNum: 128
In addition to setting the default PG number for each pool created, each Ceph pool created for OpenStack can have its own PG number. TripleO supports customization of these values by using a syntax like the following:
parameter_defaults:
CephPools:
- {"name": backups, "pg_num": 512, "pgp_num": 512, "application": rbd}
- {"name": volumes, "pg_num": 1024, "pgp_num": 1024, "application": rbd}
- {"name": vms, "pg_num": 512, "pgp_num": 512, "application": rbd}
- {"name": images, "pg_num": 128, "pgp_num": 128, "application": rbd}
Regardless of if the Deployed Ceph feature is used, pools will always be created during overcloud deployment as documented above. Additional pools may also be created directly via the Ceph command line tools.
Overriding CRUSH rules¶
To deploy Ceph pools with custom CRUSH Map Rules use the CephCrushRules parameter to define a list of named rules and then associate the rule_name per pool with the CephPools parameter:
parameter_defaults:
CephCrushRules:
- name: HDD
root: default
type: host
class: hdd
default: true
- name: SSD
root: default
type: host
class: ssd
default: false
CephPools:
- {'name': 'slow_pool', 'rule_name': 'HDD', 'application': 'rbd'}
- {'name': 'fast_pool', 'rule_name': 'SSD', 'application': 'rbd'}
Regardless of if the Deployed Ceph feature is used, custom CRUSH rules may be created during overcloud deployment as documented above. CRUSH rules may also be created directly via the Ceph command line tools.
Overriding CephX Keys¶
TripleO will create a Ceph cluster with a CephX key file for OpenStack RBD client connections that is shared by the Nova, Cinder, and Glance services to read and write to their pools. Not only will the keyfile be created but the Ceph cluster will be configured to accept connections when the key file is used. The file will be named ceph.client.openstack.keyring and it will be stored in /etc/ceph within the containers, but on the container host it will be stored in a location defined by a TripleO exposed parameter which defaults to /var/lib/tripleo-config/ceph.
The keyring file is created using the following defaults:
CephClusterName: ‘ceph’
CephClientUserName: ‘openstack’
CephClientKey: This value is randomly generated per Heat stack. If it is overridden the recommendation is to set it to the output of ceph-authtool –gen-print-key.
If the above values are overridden, the keyring file will have a different name and different content. E.g. if CephClusterName was set to ‘foo’ and CephClientUserName was set to ‘bar’, then the keyring file would be called foo.client.bar.keyring and it would contain the line [client.bar].
The CephExtraKeys parameter may be used to generate additional key files containing other key values and should contain a list of maps where each map describes an additional key. The syntax of each map must conform to what the ceph-ansible/library/ceph_key.py Ansible module accepts. The CephExtraKeys parameter should be used like this:
CephExtraKeys:
- name: "client.glance"
caps:
mgr: "allow *"
mon: "profile rbd"
osd: "profile rbd pool=images"
key: "AQBRgQ9eAAAAABAAv84zEilJYZPNuJ0Iwn9Ndg=="
mode: "0600"
If the above is used, in addition to the ceph.client.openstack.keyring file, an additional file called ceph.client.glance.keyring will be created which contains:
[client.glance]
key = AQBRgQ9eAAAAABAAv84zEilJYZPNuJ0Iwn9Ndg==
caps mgr = "allow *"
caps mon = "profile rbd"
caps osd = "profile rbd pool=images"
The Ceph cluster will also allow the above key file to be used to connect to the images pool. Ceph RBD clients which are external to the overcloud could then use this CephX key to connect to the images pool used by Glance. The default Glance deployment defined in the Heat stack will continue to use the ceph.client.openstack.keyring file unless that Glance configuration itself is overridden.
Regardless of if the Deployed Ceph feature is used, CephX keys may be created during overcloud deployment as documented above. Additional CephX keys may also be created directly via the Ceph command line tools.
Enabling cephadm debug mode¶
TripleO can deploy the Ceph cluster enabling the cephadm backend in debug mode; this is useful for troubleshooting purposes, and can be activated by using a syntax like the following:
parameter_defaults:
CephAdmDebug: true
After step 2, when the Ceph cluster is up and running, after SSH’ing into one of your controller nodes run:
sudo cephadm shell ceph -W cephadm --watch-debug
The command above shows a more verbose cephadm execution, and it’s useful to identify potential issues with the deployment of the Ceph cluster.
Accessing the Ceph Command Line¶
After step 2 of the overcloud deployment is completed you can login to check the status of your Ceph cluster. By default the Ceph Monitor containers will be running on the Controller nodes. After SSH’ing into one of your controller nodes run sudo cephadm shell. An example of what you might see is below:
[stack@standalone ~]$ sudo cephadm shell
Inferring fsid 65e8d744-eaec-4ff1-97be-2551d452426d
Inferring config /var/lib/ceph/65e8d744-eaec-4ff1-97be-2551d452426d/mon.standalone.localdomain/config
Using recent ceph image quay.ceph.io/ceph-ci/daemon@sha256:6b3c720e58ae84b502bd929d808ba63a1e9b91f710418be9df3ee566227546c0
[ceph: root@standalone /]# ceph -s
cluster:
id: 65e8d744-eaec-4ff1-97be-2551d452426d
health: HEALTH_OK
services:
mon: 1 daemons, quorum standalone.localdomain (age 61m)
mgr: standalone.localdomain.saojan(active, since 61m)
osd: 1 osds: 1 up (since 61m), 1 in (since 61m)
rgw: 1 daemon active (1 hosts, 1 zones)
data:
pools: 8 pools, 201 pgs
objects: 315 objects, 24 KiB
usage: 19 MiB used, 4.6 GiB / 4.7 GiB avail
pgs: 201 active+clean
[ceph: root@standalone /]#
If you need to make updates to your Ceph deployment use the Ceph Orchestrator.
Scenario: Deploy Ceph with TripleO and Metalsmith¶
Deploy the hardware as described in Provisioning Baremetal Before Overcloud Deploy and include nodes with in the CephStorage role. For example, the following could be the content of ~/overcloud_baremetal_deploy.yaml:
- name: Controller
count: 3
instances:
- hostname: controller-0
name: controller-0
- hostname: controller-1
name: controller-1
- hostname: controller-2
name: controller-2
- name: CephStorage
count: 3
instances:
- hostname: ceph-0
name: ceph-0
- hostname: ceph-1
name: ceph-2
- hostname: ceph-2
name: ceph-2
- name: Compute
count: 1
instances:
- hostname: compute-0
name: compute-0
which is passed to the following command:
openstack overcloud node provision \
--stack overcloud \
--output ~/overcloud-baremetal-deployed.yaml \
~/overcloud_baremetal_deploy.yaml
If desired at this stage, then Ceph may be deployed early as described in Deployed Ceph. Otherwise Ceph may be deployed during the overcloud deployment. Either way, as described in Provisioning Baremetal Before Overcloud Deploy, pass ~/overcloud_baremetal_deploy.yaml as input, along with /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml and cephadm-overrides.yaml described above, to the openstack overcloud deploy command.
Scenario: Scale Up Ceph with TripleO and Metalsmith¶
Modify the ~/overcloud_baremetal_deploy.yaml file described above to add more CephStorage nodes. In the example below the number of storage nodes is doubled:
- name: CephStorage
count: 6
instances:
- hostname: ceph-0
name: ceph-0
- hostname: ceph-1
name: ceph-2
- hostname: ceph-2
name: ceph-2
- hostname: ceph-3
name: ceph-3
- hostname: ceph-4
name: ceph-4
- hostname: ceph-5
name: ceph-5
As described in Provisioning Baremetal Before Overcloud Deploy, re-run the same openstack overcloud node provision command with the updated ~/overcloud_baremetal_deploy.yaml file. This will result in the three new storage nodes being provisioned and output an updated copy of ~/overcloud-baremetal-deployed.yaml. The updated copy will have the CephStorageCount changed from 3 to 6 and the DeployedServerPortMap and HostnameMap will contain the new storage nodes.
After the three new storage nodes are deployed run the same openstack overcloud deploy command as described in the previous section with updated copy of ~/overcloud-baremetal-deployed.yaml. The additional Ceph Storage nodes will be added to the Ceph and the increased capacity will available.
In particular, the following will happen as a result of running openstack overcloud deploy:
The storage networks and firewall rules will be appropriately configured on the new CephStorage nodes
The ceph-admin user will be created on the new CephStorage nodes
The ceph-admin user’s public SSH key will be distributed to the new CephStorage nodes so that cephadm can use SSH to add extra nodes
If a new host with the Ceph Mon or Ceph Mgr service is being added, then the private SSH key will also be added to that node.
An updated Ceph spec will be generated and installed on the bootstrap node, i.e. /home/ceph-admin/specs/ceph_spec.yaml on the bootstrap node will contain new entries for the new CephStorage nodes.
The cephadm bootstrap process will be skipped because cephadm ls will indicate that Ceph containers are already running.
The updated spec will be applied and cephadm will schedule the new nodes to join the cluster.
Scenario: Scale Down Ceph with TripleO and Metalsmith¶
Warning
This procedure is only possible if the Ceph cluster has the capacity to lose OSDs.
Before using TripleO to remove hardware which is part of a Ceph cluster, use Ceph orchestrator to deprovision the hardware gracefully. This example uses commands from the OSD Service Documentation for cephadm to remove the OSDs, and their host, before using TripleO to scale down the Ceph storage nodes.
Start a Ceph shell as described in “Accessing the Ceph Command Line” above and identify the OSDs to be removed by server. In the following example we will identify the OSDs of the host ceph-2:
[ceph: root@oc0-controller-0 /]# ceph osd tree
ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF
-1 0.58557 root default
... <redacted>
-7 0.19519 host ceph-2
5 hdd 0.04880 osd.5 up 1.00000 1.00000
7 hdd 0.04880 osd.7 up 1.00000 1.00000
9 hdd 0.04880 osd.9 up 1.00000 1.00000
11 hdd 0.04880 osd.11 up 1.00000 1.00000
... <redacted>
[ceph: root@oc0-controller-0 /]#
As per the example above the ceph-2 host has OSDs 5,7,9,11 which can be removed by running ceph orch osd rm 5 7 9 11. For example:
[ceph: root@oc0-controller-0 /]# ceph orch osd rm 5 7 9 11
Scheduled OSD(s) for removal
[ceph: root@oc0-controller-0 /]# ceph orch osd rm status
OSD_ID HOST STATE PG_COUNT REPLACE FORCE DRAIN_STARTED_AT
7 ceph-2 draining 27 False False 2021-04-23 21:35:51.215361
9 ceph-2 draining 8 False False 2021-04-23 21:35:49.111500
11 ceph-2 draining 14 False False 2021-04-23 21:35:50.243762
[ceph: root@oc0-controller-0 /]#
Use ceph orch osd rm status to check the status:
[ceph: root@oc0-controller-0 /]# ceph orch osd rm status
OSD_ID HOST STATE PG_COUNT REPLACE FORCE DRAIN_STARTED_AT
7 ceph-2 draining 34 False False 2021-04-23 21:35:51.215361
11 ceph-2 done, waiting for purge 0 False False 2021-04-23 21:35:50.243762
[ceph: root@oc0-controller-0 /]#
Only proceed if ceph orch osd rm status returns no output.
Remove the host with ceph orch host rm <HOST>. For example:
[ceph: root@oc0-controller-0 /]# ceph orch host rm ceph-2
Removed host 'ceph-2'
[ceph: root@oc0-controller-0 /]#
Now that the host and OSDs have been logically removed from the Ceph cluster proceed to remove the host from the overcloud as described in the “Scaling Down” section of Provisioning Baremetal Before Overcloud Deploy.
Scenario: Deploy Hyperconverged Ceph¶
Use a command like the following to create a roles.yaml file containing a standard Controller role and a ComputeHCI role:
openstack overcloud roles generate Controller ComputeHCI -o ~/roles.yaml
The ComputeHCI role is a Compute node which also runs co-located Ceph OSD daemons. This kind of service co-location is referred to as HCI, or hyperconverged infrastructure. See the Deploying with Composable Services documentation for details on roles and services.
When collocating Nova Compute and Ceph OSD services boundaries can be set to reduce contention for CPU and Memory between the two services. This is possible by adding parameters to cephadm-overrides.yaml like the following:
parameter_defaults:
CephHciOsdType: hdd
CephHciOsdCount: 4
CephConfigOverrides:
osd:
osd_memory_target_autotune: true
osd_numa_auto_affinity: true
mgr:
mgr/cephadm/autotune_memory_target_ratio: 0.2
The CephHciOsdType and CephHciOsdCount parameters are used by the Derived Parameters workflow to tune the Nova scheduler to not allocate a certain amount of memory and CPU from the hypervisor to virtual machines so that Ceph can use them instead. See the Derived Parameters documentation for details. If you do not use Derived Parameters workflow, then at least set the NovaReservedHostMemory to the number of OSDs multipled by 5 GB per OSD per host.
The CephConfigOverrides map passes Ceph OSD parameters to limit the CPU and memory used by the OSDs.
The osd_memory_target_autotune is set to true so that the OSD daemons will adjust their memory consumption based on the osd_memory_target config option. The autotune_memory_target_ratio defaults to 0.7. So 70% of the total RAM in the system is the starting point, from which any memory consumed by non-autotuned Ceph daemons are subtracted, and then the remaining memory is divided by the OSDs (assuming all OSDs have osd_memory_target_autotune true). For HCI deployments the mgr/cephadm/autotune_memory_target_ratio can be set to 0.2 so that more memory is available for the Nova Compute service. This has the same effect as setting the ceph-ansible is_hci parameter to true.
A two NUMA node system can host a latency sensitive Nova workload on one NUMA node and a Ceph OSD workload on the other NUMA node. To configure Ceph OSDs to use a specific NUMA node (and not the one being used by the Nova Compute workload) use either of the following Ceph OSD configurations:
osd_numa_node sets affinity to a numa node (-1 for none)
osd_numa_auto_affinity automatically sets affinity to the NUMA node where storage and network match
If there are network interfaces on both NUMA nodes and the disk controllers are NUMA node 0, then use a network interface on NUMA node 0 for the storage network and host the Ceph OSD workload on NUMA node 0. Then host the Nova workload on NUMA node 1 and have it use the network interfaces on NUMA node 1. Setting osd_numa_auto_affinity, to true, as in the example cephadm-overrides.yaml file above, should result in this configuration. Alternatively, the osd_numa_node could be set directly to 0 and osd_numa_auto_affinity could be unset so that it will default to false.
When a hyperconverged cluster backfills as a result of an OSD going offline, the backfill process can be slowed down. In exchange for a slower recovery, the backfill activity has less of an impact on the collocated Compute workload. Ceph Pacific has the following defaults to control the rate of backfill activity:
parameter_defaults:
CephConfigOverrides:
osd:
osd_recovery_op_priority: 3
osd_max_backfills: 1
osd_recovery_max_active_hdd: 3
osd_recovery_max_active_ssd: 10
It is not necessary to pass the above as they are the default values, but if these values need to be deployed with different values modify an example like the above before deployment. If the values need to be adjusted after the deployment use ceph config set osd <key> <value>.
Deploy the overcloud as described in “Scenario: Deploy Ceph with TripleO and Metalsmith” but use the -r option to include generated roles.yaml file and the -e option with the cephadm-overrides.yaml file containing the HCI tunings described above.
The examples above may be used to tune a hyperconverged system during deployment. If the values need to be changed after deployment, then use the ceph orchestrator command to set them directly.
After deployment start a Ceph shell as described in “Accessing the Ceph Command Line” and confirm the above values were applied. For example, to check that the NUMA and memory target auto tuning run commands lke this:
[ceph: root@oc0-controller-0 /]# ceph config dump | grep numa
osd advanced osd_numa_auto_affinity true
[ceph: root@oc0-controller-0 /]# ceph config dump | grep autotune
osd advanced osd_memory_target_autotune true
[ceph: root@oc0-controller-0 /]# ceph config get mgr mgr/cephadm/autotune_memory_target_ratio
0.200000
[ceph: root@oc0-controller-0 /]#
We can then confirm that a specific OSD, e.g. osd.11, inherited those values with commands like this:
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_memory_target
4294967296
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_memory_target_autotune
true
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_numa_auto_affinity
true
[ceph: root@oc0-controller-0 /]#
To confirm that the default backfill values are set for the same example OSD, use commands like this:
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_recovery_op_priority
3
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_max_backfills
1
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_recovery_max_active_hdd
3
[ceph: root@oc0-controller-0 /]# ceph config get osd.11 osd_recovery_max_active_ssd
10
[ceph: root@oc0-controller-0 /]#
The above example assumes that Deployed Ceph is not used.
Add the Ceph Dashboard to a Overcloud deployment¶
During the overcloud deployment most of the Ceph daemons can be added and configured. To deploy the ceph dashboard include the ceph-dashboard.yaml environment file as in the following example:
openstack overcloud deploy --templates -e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml -e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/ceph-dashboard.yaml
The command above will include the ceph dashboard related services and generates all the cephadm required variables to render the monitoring stack related spec that can be applied against the deployed Ceph cluster. When the deployment has been completed the Ceph dashboard containers, including prometheus and grafana, will be running on the controller nodes and will be accessible using the port 3100 for grafana and 9092 for prometheus; since this service is only internal and doesn’t listen on the public vip, users can reach both grafana and the exposed ceph dashboard using the controller provisioning network vip on the specified port (8444 is the default for a generic overcloud deployment). The resulting deployment will be composed by an external stack made by grafana, prometheus, alertmanager, node-exporter containers and the ceph dashboard mgr module that acts as the backend for this external stack, embedding the grafana layouts and showing the ceph cluster specific metrics coming from prometheus. The Ceph Dashboard backend services run on the specified CephDashboardNetwork and CephGrafanaNetwork, while the high availability is realized by haproxy and Pacemaker. The Ceph Dashboard frontend is fully integrated with the tls-everywhere framework, hence providing the tls environments files will trigger the certificate request for both grafana and the ceph dashboard: the generated crt and key files are then configured by cephadm, resulting in a key-value pair within the Ceph orchestrator, which is able to mount the required files to the dashboard related containers. The Ceph Dashboard admin user role is set to read-only mode by default for safe monitoring of the Ceph cluster. To permit an admin user to have elevated privileges to alter elements of the Ceph cluster with the Dashboard, the operator can change the default. For this purpose, TripleO exposes a parameter that can be used to change the Ceph Dashboard admin default mode. Log in to the undercloud as stack user and create the ceph_dashboard_admin.yaml environment file with the following content:
parameter_defaults:
CephDashboardAdminRO: false
Run the overcloud deploy command to update the existing stack and include the environment file created with all other environment files that are already part of the existing deployment:
openstack overcloud deploy --templates -e <existing_overcloud_environment_files> -e ceph_dashboard_admin.yml
The ceph dashboard will also work with composable networks. In order to isolate the monitoring access for security purposes, operators can take advantage of composable networks and access the dashboard through a separate network vip. By doing this, it’s not necessary to access the provisioning network and separate authorization profiles may be implemented. To deploy the overcloud with the ceph dashboard composable network we need first to generate the controller specific role created for this scenario:
openstack overcloud roles generate -o /home/stack/roles_data.yaml ControllerStorageDashboard Compute BlockStorage ObjectStorage CephStorage
Finally, run the overcloud deploy command including the new generated roles_data.yaml and the network_data_dashboard.yaml file that will trigger the generation of this new network. The final overcloud command must look like the following:
openstack overcloud deploy --templates -r /home/stack/roles_data.yaml -n /usr/share/openstack-tripleo-heat-templates/network_data_dashboard.yaml -e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml -e ~/my-ceph-settings.yaml
