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Chapter 5. Customizing the Ceph Storage cluster
To deploy containerized Ceph Storage you must include the /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml file during overcloud deployment. This environment file also defines the following resources:
CephAnsibleDisksConfig- This resource maps the Ceph Storage node disk layout. For more information, see Section 5.2, “Mapping the Ceph Storage node disk layout”.
CephConfigOverrides- This resource applies all other custom settings to your Ceph cluster.
Use these resources to override any defaults that the director sets for containerized Ceph Storage.
The /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml environment file uses playbooks provided by the ceph-ansible package. As such, you must install this package on your undercloud first:
$ sudo dnf install ceph-ansible
To customize your Ceph cluster, define your custom parameters in a new environment file, for example, /home/stack/templates/ceph-config.yaml. You can arbitrarily apply global Ceph cluster settings using the following syntax in the parameter_defaults section of your environment file:
parameter_defaults:
CephConfigOverrides:
KEY:VALUE
Replace KEY and VALUE with the Ceph cluster settings that you want to apply. For example, consider the following snippet:
parameter_defaults:
CephConfigOverrides:
max_open_files: 131072This configuration results in the following settings defined in the configuration file of your Ceph cluster:
[global] max_open_files: 131072
For more information about supported parameters, see the Red Hat Ceph Storage Configuration Guide.
The CephConfigOverrides parameter applies only to the [global] section of the ceph.conf file. You cannot make changes to other sections, for example the [osd] section, with the CephConfigOverrides parameter.
The ceph-ansible tool has a group_vars directory that you can use to set many different Ceph parameters. For more information, see Installing a Red Hat Ceph Storage cluster in the Installation Guide.
To change the variable defaults in director, you can use the CephAnsibleExtraConfig parameter to pass the new values in heat environment files. For example, to set the ceph-ansible group variable journal_size to 40960, create an environment file with the following journal_size definition:
parameter_defaults:
CephAnsibleExtraConfig:
journal_size: 40960
Change ceph-ansible group variables with the override parameters; do not edit group variables directly in the /usr/share/ceph-ansible directory on the undercloud.
5.1. Ceph containers for Red Hat OpenStack Platform with Ceph Storage
A Ceph container is required to configure OpenStack Platform to use Ceph, even with an external Ceph cluster. To be compatible with Red Hat Enterprise Linux 8, OpenStack Platform 15 requires Red Hat Ceph Storage 4. The Ceph Storage 4 container is hosted at registry.redhat.io, a registry which requires authentication.
You can use the heat environment parameter ContainerImageRegistryCredentials to authenticate at registry.redhat.io, as described in Container image preparation parameters.
5.2. Mapping the Ceph Storage node disk layout
When you deploy containerized Ceph Storage, you must map the disk layout and specify dedicated block devices for the Ceph OSD service. You can perform this mapping in the environment file that you created earlier to define your custom Ceph parameters: /home/stack/templates/ceph-config.yaml.
Use the CephAnsibleDisksConfig resource in parameter_defaults to map your disk layout. This resource uses the following variables:
| Variable | Required? | Default value (if unset) | Description |
|---|---|---|---|
| osd_scenario | Yes | lvm |
The |
| devices | Yes | NONE. Variable must be set. | A list of block devices that you want to use for OSDs on the node. |
| dmcrypt | No | false |
Sets whether data stored on OSDs is encrypted ( |
| osd_objectstore | No | bluestore | Sets the storage back end used by Ceph. |
5.2.1. Using BlueStore
To specify the block devices that you want to use as Ceph OSDs, use a variation of the following snippet:
parameter_defaults:
CephAnsibleDisksConfig:
devices:
- /dev/sdb
- /dev/sdc
- /dev/sdd
- /dev/nvme0n1
osd_scenario: lvm
osd_objectstore: bluestore
Because /dev/nvme0n1 is in a higher performing device class, the example parameter defaults produce three OSDs that run on /dev/sdb, /dev/sdc, and /dev/sdd. The three OSDs use /dev/nvme0n1 as a BlueStore WAL device. The ceph-volume tool does this by using the batch subcommand. The same setup is duplicated for each Ceph storage node and assumes uniform hardware. If the BlueStore WAL data resides on the same disks as the OSDs, then change the parameter defaults:
parameter_defaults:
CephAnsibleDisksConfig:
devices:
- /dev/sdb
- /dev/sdc
- /dev/sdd
osd_scenario: lvm
osd_objectstore: bluestore5.2.2. Referring to devices with persistent names
In some nodes, disk paths, such as /dev/sdb and /dev/sdc, may not point to the same block device during reboots. If this is the case with your CephStorage nodes, specify each disk with the /dev/disk/by-path/ symlink to ensure that the block device mapping is consistent throughout deployments:
parameter_defaults:
CephAnsibleDisksConfig:
devices:
- /dev/disk/by-path/pci-0000:03:00.0-scsi-0:0:10:0
- /dev/disk/by-path/pci-0000:03:00.0-scsi-0:0:11:0
Because you must set the list of OSD devices prior to overcloud deployment, it may not be possible to identify and set the PCI path of disk devices. In this case, gather the /dev/disk/by-path/symlink data for block devices during introspection.
In the following example, run the first command to download the introspection data from the undercloud Object Storage service (swift) for the server b08-h03-r620-hci and saves the data in a file called b08-h03-r620-hci.json. Run the second command to grep for “by-path”. The output of this command contains the unique /dev/disk/by-path values that you can use to identify disks.
(undercloud) [stack@b08-h02-r620 ironic]$ openstack baremetal introspection data save b08-h03-r620-hci | jq . > b08-h03-r620-hci.json
(undercloud) [stack@b08-h02-r620 ironic]$ grep by-path b08-h03-r620-hci.json
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:0:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:1:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:3:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:4:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:5:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:6:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:7:0",
"by_path": "/dev/disk/by-path/pci-0000:02:00.0-scsi-0:2:0:0",For more information about naming conventions for storage devices, see Persistent Naming.
For details about each journaling scenario and disk mapping for containerized Ceph Storage, see the OSD Scenarios section of the project documentation for ceph-ansible.
5.3. Assigning custom attributes to different Ceph pools
By default, Ceph pools created through the director have the same placement group (pg_num and pgp_num) and sizes. You can use either method in Chapter 5, Customizing the Ceph Storage cluster to override these settings globally; that is, doing so will apply the same values for all pools.
You can also apply different attributes to each Ceph pool. To do so, use the CephPools parameter, as in:
parameter_defaults:
CephPools:
- name: POOL
pg_num: 128
application: rbd
Replace POOL with the name of the pool you want to configure along with the pg_num setting to indicate number of placement groups. This overrides the default pg_num for the specified pool.
If you use the CephPools parameter, you must also specify the application type. The application type for Compute, Block Storage, and Image Storage should be rbd, as shown in the examples, but depending on what the pool will be used for, you may need to specify a different application type. For example, the application type for the gnocchi metrics pool is openstack_gnocchi. See Enable Application in the Storage Strategies Guide for more information.
If you do not use the CephPools parameter, director sets the appropriate application type automatically, but only for the default pool list.
You can also create new custom pools through the CephPools parameter. For example, to add a pool called custompool:
parameter_defaults:
CephPools:
- name: custompool
pg_num: 128
application: rbdThis creates a new custom pool in addition to the default pools.
For typical pool configurations of common Ceph use cases, see the Ceph Placement Groups (PGs) per Pool Calculator. This calculator is normally used to generate the commands for manually configuring your Ceph pools. In this deployment, the director will configure the pools based on your specifications.
Red Hat Ceph Storage 3 (Luminous) introduces a hard limit on the maximum number of PGs an OSD can have, which is 200 by default. Do not override this parameter beyond 200. If there is a problem because the Ceph PG number exceeds the maximum, adjust the pg_num per pool to address the problem, not the mon_max_pg_per_osd.
5.4. Mapping the disk layout to non-homogeneous Ceph Storage nodes
By default, all nodes of a role that host Ceph OSDs (indicated by the OS::TripleO::Services::CephOSD service in roles_data.yaml), for example CephStorage or ComputeHCI nodes, use the global devices list set in Section 5.2, “Mapping the Ceph Storage node disk layout”. This assumes that all of these servers have homogeneous hardware. If a subset of these servers do not have homogeneous hardware, then director needs to be aware that each of these servers has a different devices list. This is known as a node-specific disk configuration.
To pass director a node-specific disk configuration, a heat environment file, such as node-spec-overrides.yaml, must be passed to the openstack overcloud deploy command and the file content must identify each server by a machine unique UUID and a list of local variables that override the global variables.
The machine unique UUID may be extracted for each individual server or from the Ironic database.
To locate the UUID for an individual server, log in to the server and run:
dmidecode -s system-uuid
To extract the UUID from the Ironic database, run the following command on the undercloud:
openstack baremetal introspection data save NODE-ID | jq .extra.system.product.uuid
If the undercloud.conf does not have inspection_extras = true prior to undercloud installation or upgrade and introspection, then the machine unique UUID will not be in the Ironic database.
The machine unique UUID is not the Ironic UUID.
A valid node-spec-overrides.yaml file may look like the following:
parameter_defaults:
NodeDataLookup: {"32E87B4C-C4A7-418E-865B-191684A6883B": {"devices": ["/dev/sdc"]}}
All lines after the first two lines must be valid JSON. An easy way to verify that the JSON is valid is to use the jq command. For example:
-
Remove the first two lines (
parameter_defaults:andNodeDataLookup:) from the file temporarily. -
Run
cat node-spec-overrides.yaml | jq .
As the node-spec-overrides.yaml file grows, you can also use jq to ensure that the embedded JSON is valid. For example, use the following to verify that JSON defines the correct length of the devices list before starting the deployment.
(undercloud) [stack@b08-h02-r620 tht]$ cat node-spec-c05-h17-h21-h25-6048r.yaml | jq '.[] | .devices | length' 33 30 33 (undercloud) [stack@b08-h02-r620 tht]$
In the above example, the node-spec-c05-h17-h21-h25-6048r.yaml has three servers in rack c05 in which slots h17, h21, and h25 are missing disks. A more complicated example is included at the end of this section.
After the JSON has been validated, add back the two lines which makes it a valid environment YAML file (parameter_defaults: and NodeDataLookup:) and include it with a -e in the deployment.
In the example below, the updated heat environment file uses NodeDataLookup for Ceph deployment. All of the servers had a devices list with 35 disks except one of them had a disk missing. This environment file overrides the default devices list for only that single node and gives it the list of 34 disks it should use instead of the global list.
parameter_defaults:
# c05-h01-6048r is missing scsi-0:2:35:0 (00000000-0000-0000-0000-0CC47A6EFD0C)
NodeDataLookup: {
"00000000-0000-0000-0000-0CC47A6EFD0C": {
"devices": [
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:1:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:32:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:2:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:3:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:4:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:5:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:6:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:33:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:7:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:8:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:34:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:9:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:10:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:11:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:12:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:13:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:14:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:15:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:16:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:17:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:18:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:19:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:20:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:21:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:22:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:23:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:24:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:25:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:26:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:27:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:28:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:29:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:30:0",
"/dev/disk/by-path/pci-0000:03:00.0-scsi-0:2:31:0"
]
}
}5.5. Increasing the restart delay for large Ceph clusters
During deployment, Ceph services such as OSDs and Monitors, are restarted and the deployment does not continue until the service is running again. Ansible waits 15 seconds (the delay) and checks 5 times for the service to start (the retries). If the service does not restart, the deployment stops so the operator can intervene.
Depending on the size of the Ceph cluster, you may need to increase the retry or delay values. The exact names of these parameters and their defaults are as follows:
health_mon_check_retries: 5 health_mon_check_delay: 15 health_osd_check_retries: 5 health_osd_check_delay: 15
Procedure
Update the
CephAnsibleExtraConfigparameter to change the default delay and retry values:parameter_defaults: CephAnsibleExtraConfig: health_osd_check_delay: 40 health_osd_check_retries: 30 health_mon_check_delay: 20 health_mon_check_retries: 10This example makes the cluster check 30 times and wait 40 seconds between each check for the Ceph OSDs, and check 20 times and wait 10 seconds between each check for the Ceph MONs.
-
To incorporate the changes, pass the updated
yamlfile with-eusingopenstack overcloud deploy.
5.6. Overriding Ansible environment variables
The Red Hat OpenStack Platform Workflow service (mistral) uses Ansible to configure Ceph Storage, but you can customize the Ansible environment by using Ansible environment variables.
Procedure
To override an ANSIBLE_* environment variable, use the CephAnsibleEnvironmentVariables heat template parameter.
This example configuration increases the number of forks and SSH retries:
parameter_defaults:
CephAnsibleEnvironmentVariables:
ANSIBLE_SSH_RETRIES: '6'
DEFAULT_FORKS: '35'For more information about Ansible environment variables, see Ansible Configuration Settings.
For more information about how to customize your Ceph Storage cluster, see Customizing the Ceph Storage cluster.
