Chapter 8. Deploying on OpenStack with rootVolume and etcd on local disk Important Deploying on Red Hat OpenStack Platform (RHOSP) with rootVolume and etcd on local disk is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope . As a day 2 operation, you can resolve and prevent performance issues of your Red Hat OpenStack Platform (RHOSP) installation by moving etcd from a root volume (provided by OpenStack Cinder) to a dedicated ephemeral local disk. 8.1. Deploying RHOSP on local disk If you have an existing RHOSP cloud, you can move etcd from that cloud to a dedicated ephemeral local disk. Warning This procedure is for testing etcd on a local disk only and should not be used on production clusters. In certain cases, complete loss of the control plane can occur. For more information, see "Overview of backup and restore operation" under "Backup and restore". Prerequisites You have an OpenStack cloud with a working Cinder. Your OpenStack cloud has at least 75 GB of available storage to accommodate 3 root volumes for the OpenShift control plane. The OpenStack cloud is deployed with Nova ephemeral storage that uses a local storage backend and not rbd . Procedure Create a Nova flavor for the control plane with at least 10 GB of ephemeral disk by running the following command, replacing the values for --ram , --disk , and <flavor_name> based on your environment: USD openstack flavor create --<ram 16384> --<disk 0> --ephemeral 10 --vcpus 4 <flavor_name> Deploy a cluster with root volumes for the control plane; for example: Example YAML file # ... controlPlane: name: master platform: openstack: type: USD{CONTROL_PLANE_FLAVOR} rootVolume: size: 25 types: - USD{CINDER_TYPE} replicas: 3 # ... Deploy the cluster you created by running the following command: USD openshift-install create cluster --dir <installation_directory> 1 1 For <installation_directory> , specify the location of the customized ./install-config.yaml file that you previously created. Verify that the cluster you deployed is healthy before proceeding to the step by running the following command: USD oc wait clusteroperators --all --for=condition=Progressing=false 1 1 Ensures that the cluster operators are finished progressing and that the cluster is not deploying or updating. Edit the ControlPlaneMachineSet (CPMS) to add the additional block ephemeral device that is used by etcd by running the following command: USD oc patch ControlPlaneMachineSet/cluster -n openshift-machine-api --type json -p ' 1 [ { "op": "add", "path": "/spec/template/machines_v1beta1_machine_openshift_io/spec/providerSpec/value/additionalBlockDevices", 2 "value": [ { "name": "etcd", "sizeGiB": 10, "storage": { "type": "Local" 3 } } ] } ] ' 1 Applies the JSON patch to the ControlPlaneMachineSet custom resource (CR). 2 Specifies the path where the additionalBlockDevices are added. 3 Adds the etcd devices with at least local storage of 10 GB to the cluster. You can specify values greater than 10 GB as long as the etcd device fits the Nova flavor. For example, if the Nova flavor has 15 GB, you can create the etcd device with 12 GB. Verify that the control plane machines are healthy by using the following steps: Wait for the control plane machine set update to finish by running the following command: USD oc wait --timeout=90m --for=condition=Progressing=false controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster Verify that the 3 control plane machine sets are updated by running the following command: USD oc wait --timeout=90m --for=jsonpath='{.status.updatedReplicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster Verify that the 3 control plane machine sets are healthy by running the following command: USD oc wait --timeout=90m --for=jsonpath='{.status.replicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster Verify that the ClusterOperators are not progressing in the cluster by running the following command: USD oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false Verify that each of the 3 control plane machines has the additional block device you previously created by running the following script: USD cp_machines=USD(oc get machines -n openshift-machine-api --selector='machine.openshift.io/cluster-api-machine-role=master' --no-headers -o custom-columns=NAME:.metadata.name) 1 if [[ USD(echo "USD{cp_machines}" | wc -l) -ne 3 ]]; then exit 1 fi 2 for machine in USD{cp_machines}; do if ! oc get machine -n openshift-machine-api "USD{machine}" -o jsonpath='{.spec.providerSpec.value.additionalBlockDevices}' | grep -q 'etcd'; then exit 1 fi 3 done 1 Retrieves the control plane machines running in the cluster. 2 Iterates over machines which have an additionalBlockDevices entry with the name etcd . 3 Outputs the name of every control plane machine which has an additionalBlockDevice named etcd . Create a file named 98-var-lib-etcd.yaml by using the following YAML file: Warning This procedure is for testing etcd on a local disk and should not be used on a production cluster. In certain cases, complete loss of the control plane can occur. For more information, see "Overview of backup and restore operation" under "Backup and restore". apiVersion: machineconfiguration.openshift.io/v1 kind: MachineConfig metadata: labels: machineconfiguration.openshift.io/role: master name: 98-var-lib-etcd spec: config: ignition: version: 3.4.0 systemd: units: - contents: | [Unit] Description=Mount local-etcd to /var/lib/etcd [Mount] What=/dev/disk/by-label/local-etcd 1 Where=/var/lib/etcd Type=xfs Options=defaults,prjquota [Install] WantedBy=local-fs.target enabled: true name: var-lib-etcd.mount - contents: | [Unit] Description=Create local-etcd filesystem DefaultDependencies=no After=local-fs-pre.target ConditionPathIsSymbolicLink=!/dev/disk/by-label/local-etcd 2 [Service] Type=oneshot RemainAfterExit=yes ExecStart=/bin/bash -c "[ -L /dev/disk/by-label/ephemeral0 ] || ( >&2 echo Ephemeral disk does not exist; /usr/bin/false )" ExecStart=/usr/sbin/mkfs.xfs -f -L local-etcd /dev/disk/by-label/ephemeral0 3 [Install] RequiredBy=dev-disk-by\x2dlabel-local\x2detcd.device enabled: true name: create-local-etcd.service - contents: | [Unit] Description=Migrate existing data to local etcd After=var-lib-etcd.mount Before=crio.service 4 Requisite=var-lib-etcd.mount ConditionPathExists=!/var/lib/etcd/member ConditionPathIsDirectory=/sysroot/ostree/deploy/rhcos/var/lib/etcd/member 5 [Service] Type=oneshot RemainAfterExit=yes ExecStart=/bin/bash -c "if [ -d /var/lib/etcd/member.migrate ]; then rm -rf /var/lib/etcd/member.migrate; fi" 6 ExecStart=/usr/bin/cp -aZ /sysroot/ostree/deploy/rhcos/var/lib/etcd/member/ /var/lib/etcd/member.migrate ExecStart=/usr/bin/mv /var/lib/etcd/member.migrate /var/lib/etcd/member 7 [Install] RequiredBy=var-lib-etcd.mount enabled: true name: migrate-to-local-etcd.service - contents: | [Unit] Description=Relabel /var/lib/etcd After=migrate-to-local-etcd.service Before=crio.service [Service] Type=oneshot RemainAfterExit=yes ExecCondition=/bin/bash -c "[ -n \"USD(restorecon -nv /var/lib/etcd)\" ]" 8 ExecStart=/usr/sbin/restorecon -R /var/lib/etcd [Install] RequiredBy=var-lib-etcd.mount enabled: true name: relabel-var-lib-etcd.service 1 The etcd database must be mounted by the device, not a label, to ensure that systemd generates the device dependency used in this config to trigger filesystem creation. 2 Do not run if the file system dev/disk/by-label/local-etcd already exists. 3 Fails with an alert message if /dev/disk/by-label/ephemeral0 does not exist. 4 Migrates existing data to local etcd database. This config does so after /var/lib/etcd is mounted, but before CRI-O starts so etcd is not running yet. 5 Requires that etcd is mounted and does not contain a member directory, but the ostree does. 6 Cleans up any migration state. 7 Copies and moves in separate steps to ensure atomic creation of a complete member directory. 8 Performs a quick check of the mount point directory before performing a full recursive relabel. If restorecon in the file path /var/lib/etcd cannot rename the directory, the recursive rename is not performed. Create the new MachineConfig object by running the following command: USD oc create -f 98-var-lib-etcd.yaml Note Moving the etcd database onto the local disk of each control plane machine takes time. Verify that the etcd databases has been transferred to the local disk of each control plane by running the following commands: Verify that the cluster is still updating by running the following command: USD oc wait --timeout=45m --for=condition=Updating=false machineconfigpool/master Verify that the cluster is ready by running the following command: USD oc wait node --selector='node-role.kubernetes.io/master' --for condition=Ready --timeout=30s Verify that the cluster Operators are running in the cluster by running the following command: USD oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false 8.2. Additional resources Recommended etcd practices Overview of backup and restore options

Commands:
openstack flavor create --<ram 16384> --<disk 0> --ephemeral 10 --vcpus 4 <flavor_name>
controlPlane: name: master platform: openstack: type: USD{CONTROL_PLANE_FLAVOR} rootVolume: size: 25 types: - USD{CINDER_TYPE} replicas: 3
openshift-install create cluster --dir <installation_directory> 1
oc wait clusteroperators --all --for=condition=Progressing=false 1
oc patch ControlPlaneMachineSet/cluster -n openshift-machine-api --type json -p ' 1 [ { "op": "add", "path": "/spec/template/machines_v1beta1_machine_openshift_io/spec/providerSpec/value/additionalBlockDevices", 2 "value": [ { "name": "etcd", "sizeGiB": 10, "storage": { "type": "Local" 3 } } ] } ] '
oc wait --timeout=90m --for=condition=Progressing=false controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster
oc wait --timeout=90m --for=jsonpath='{.status.updatedReplicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster
oc wait --timeout=90m --for=jsonpath='{.status.replicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster
oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false
cp_machines=USD(oc get machines -n openshift-machine-api --selector='machine.openshift.io/cluster-api-machine-role=master' --no-headers -o custom-columns=NAME:.metadata.name) 1 if [[ USD(echo "USD{cp_machines}" | wc -l) -ne 3 ]]; then exit 1 fi 2 for machine in USD{cp_machines}; do if ! oc get machine -n openshift-machine-api "USD{machine}" -o jsonpath='{.spec.providerSpec.value.additionalBlockDevices}' | grep -q 'etcd'; then exit 1 fi 3 done
apiVersion: machineconfiguration.openshift.io/v1 kind: MachineConfig metadata: labels: machineconfiguration.openshift.io/role: master name: 98-var-lib-etcd spec: config: ignition: version: 3.4.0 systemd: units: - contents: | [Unit] Description=Mount local-etcd to /var/lib/etcd [Mount] What=/dev/disk/by-label/local-etcd 1 Where=/var/lib/etcd Type=xfs Options=defaults,prjquota [Install] WantedBy=local-fs.target enabled: true name: var-lib-etcd.mount - contents: | [Unit] Description=Create local-etcd filesystem DefaultDependencies=no After=local-fs-pre.target ConditionPathIsSymbolicLink=!/dev/disk/by-label/local-etcd 2 [Service] Type=oneshot RemainAfterExit=yes ExecStart=/bin/bash -c "[ -L /dev/disk/by-label/ephemeral0 ] || ( >&2 echo Ephemeral disk does not exist; /usr/bin/false )" ExecStart=/usr/sbin/mkfs.xfs -f -L local-etcd /dev/disk/by-label/ephemeral0 3 [Install] RequiredBy=dev-disk-by\x2dlabel-local\x2detcd.device enabled: true name: create-local-etcd.service - contents: | [Unit] Description=Migrate existing data to local etcd After=var-lib-etcd.mount Before=crio.service 4 Requisite=var-lib-etcd.mount ConditionPathExists=!/var/lib/etcd/member ConditionPathIsDirectory=/sysroot/ostree/deploy/rhcos/var/lib/etcd/member 5 [Service] Type=oneshot RemainAfterExit=yes ExecStart=/bin/bash -c "if [ -d /var/lib/etcd/member.migrate ]; then rm -rf /var/lib/etcd/member.migrate; fi" 6 ExecStart=/usr/bin/cp -aZ /sysroot/ostree/deploy/rhcos/var/lib/etcd/member/ /var/lib/etcd/member.migrate ExecStart=/usr/bin/mv /var/lib/etcd/member.migrate /var/lib/etcd/member 7 [Install] RequiredBy=var-lib-etcd.mount enabled: true name: migrate-to-local-etcd.service - contents: | [Unit] Description=Relabel /var/lib/etcd After=migrate-to-local-etcd.service Before=crio.service [Service] Type=oneshot RemainAfterExit=yes ExecCondition=/bin/bash -c "[ -n \"USD(restorecon -nv /var/lib/etcd)\" ]" 8 ExecStart=/usr/sbin/restorecon -R /var/lib/etcd [Install] RequiredBy=var-lib-etcd.mount enabled: true name: relabel-var-lib-etcd.service
oc create -f 98-var-lib-etcd.yaml
oc wait --timeout=45m --for=condition=Updating=false machineconfigpool/master
oc wait node --selector='node-role.kubernetes.io/master' --for condition=Ready --timeout=30s
oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false