Chapter 3. Reusing bricks and restoring configuration from backups 3.1. Host replacement prerequisites Determine which node to use as the Ansible controller node (the node from which all Ansible playbooks are executed). Red Hat recommends using a healthy node in the same cluster as the failed node as the Ansible controller node. If possible, locate a recent backup or create a new backup of the important files (disk configuration or inventory files). See Backing up important files for details. Stop brick processes and unmount file systems on the failed host, to avoid file system inconsistency issues. Check which operating system is running on your hyperconverged hosts by running the following command: Reinstall the same operating system on the failed hyperconverged host. 3.2. Preparing the cluster for host replacement Verify host state in the Administrator Portal. Log in to the Red Hat Virtualization Administrator Portal. The host is listed as NonResponsive in the Administrator Portal. Virtual machines that previously ran on this host are in the Unknown state. Click Compute Hosts and click the Action menu (...). Click Confirm host has been rebooted and confirm the operation. Verify that the virtual machines are now listed with a state of Down . Update the SSH fingerprint for the failed node. Log in to the Ansible controller node as the root user. Remove the existing SSH fingerprint for the failed node. Copy the public key from the Ansible controller node to the freshly installed node. Verify that you can log in to all hosts in the cluster, including the Ansible controller node, using key-based SSH authentication without a password. Test access using all network addresses. The following example assumes that the Ansible controller node is host1 . Use ssh-copy-id to copy the public key to any host you cannot log into without a password using this method. 3.3. Restoring disk configuration from backups Prerequisites This procedure assumes you have already performed the backup process in Chapter 2, Backing up important files and know the location of your backup files and the address of the backup host. Procedure If the new host does not have multipath configuration, blacklist the devices. Create an inventory file for the new host that defines the devices to blacklist. Run the gluster_deployment.yml playbook on this inventory file using the blacklistdevices tag. Copy backed up configuration details to the new host. Create an inventory file for host restoration. Change into the hc-ansible-deployment directory and back up the default archive_config_inventory.yml file. Edit the archive_config_inventory.yml file with details of the cluster you want to back up. hosts The backend FQDN of the host that you want to restore (this host). backup_dir The directory in which to store extracted backup files. nbde_setup If you use Network-Bound Disk Encryption, set this to true . Otherwise, set to false . upgrade Set to false . For example: Execute the archive_config.yml playbook. Run the archive_config.yml playbook using your updated inventory file with the restorefiles tag. (Optional) Configure Network-Bound Disk Encryption (NBDE) on the root disk. Create an inventory file for the new host that defines devices to encrypt. See Understanding the luks_tang_inventory.yml file for more information about these parameters. Run the luks_tang_setup.yml playbook using your inventory file and the bindtang tag. 3.4. Creating the node_replace_inventory.yml file Define your cluster hosts by creating a node_replacement_inventory.yml file. Procedure Back up the node_replace_inventory.yml file. Edit the node_replace_inventory.yml file to define your cluster. See Appendix C, Understanding the node_replace_inventory.yml file for more information about this inventory file and its parameters. 3.5. Executing the replace_node.yml playbook file The replace_node.yml playbook reconfigures a Red Hat Hyperconverged Infrastructure for Virtualization cluster to use a new node after an existing cluster node has failed. Procedure Execute the playbook. 3.6. Finalizing host replacement After you have replaced a failed host with a new host, follow these steps to ensure that the cluster is connected to the new host and properly activated. Procedure Activate the host. Log in to the Red Hat Virtualization Administrator Portal. Click Compute Hosts and observe that the replacement host is listed with a state of Maintenance . Select the host and click Management Activate . Wait for the host to reach the Up state. Attach the gluster network to the host. Click Compute Hosts and select the host. Click Network Interfaces Setup Host Networks . Drag and drop the newly created network to the correct interface. Ensure that the Verify connectivity between Host and Engine checkbox is checked. Ensure that the Save network configuration checkbox is checked. Click OK to save. Verify the health of the network. Click the Network Interfaces tab and check the state of the host's network. If the network interface enters an "Out of sync" state or does not have an IP Address, click Management Refresh Capabilities . 3.7. Verifying healing in progress After replacing a failed host with a new host, verify that your storage is healing as expected. Procedure Verify that healing is in progress. Run the following command on any hyperconverged host: The output shows a summary of healing activity on each brick in each volume, for example: Depending on brick size, volumes can take a long time to heal. You can still run and migrate virtual machines using this node while the underlying storage heals.

Commands:
pkill glusterfsd umount /gluster_bricks/{engine,vmstore,data}
nodectl info
sed -i `/ failed-host-frontend.example.com /d` /root/.ssh/known_hosts sed -i `/ failed-host-backend.example.com /d` /root/.ssh/known_hosts
ssh-copy-id root@ new-host-backend.example.com ssh-copy-id root@ new-host-frontend.example.com
ssh root@ host1-backend.example.com ssh root@ host1-frontend.example.com ssh root@ host2-backend.example.com ssh root@ host2-frontend.example.com ssh root@ new-host-backend.example.com ssh root@ new-host-frontend.example.com
ssh-copy-id root@ host-frontend.example.com ssh-copy-id root@ host-backend.example.com
hc_nodes: hosts: new-host-backend-fqdn.example.com : blacklist_mpath_devices: - sda - sdb - sdc - sdd
ansible-playbook -i blacklist-inventory.yml /etc/ansible/roles/gluster.ansible/playbooks/hc-ansible-deployment/tasks/gluster_deployment.yml --tags=blacklistdevices
mkdir /rhhi-backup scp backup-host.example.com :/backups/rhvh-node-host1-backend.example.com-backup.tar.gz /rhhi-backup tar -xvf /rhhi-backup/rhvh-node-host1-backend.example.com-backup.tar.gz -C /rhhi-backup
cd /etc/ansible/roles/gluster.ansible/playbooks/hc-ansible-deployment cp archive_config_inventory.yml archive_config_inventory.yml.bk
all: hosts: host1-backend.example.com : vars: backup_dir: /rhhi-backup nbde_setup: true upgrade: false
ansible-playbook -i archive_config_inventory.yml archive_config.yml --tags=restorefiles
hc_nodes: hosts: new-node-frontend-fqdn.example.com : blacklist_mpath_devices: - sda - sdb - sdc rootpassphrase: stronGpa55 rootdevice: /dev/sda2 networkinterface: eth1 vars: ip_version: IPv4 ip_config_method: dhcp gluster_infra_tangservers: - url: http:// tang-server.example.com : 80
ansible-playbook -i inventory.yml /etc/ansible/roles/gluster.ansible/playbooks/hc-ansible-deployment/tasks/luks_tang_setup.yml --tags=bindtang
cd /etc/ansible/roles/gluster.ansible/playbooks/hc-ansible-deployment cp node_replace_inventory.yml node_replace_inventory.yml.bk
cd /etc/ansible/roles/gluster.ansible/playbooks/hc-ansible-deployment/ ansible-playbook -i node_replace_inventory.yml tasks/replace_node.yml --tags=restorepeer
for vol in `gluster volume list`; do gluster volume heal USDvol info summary; done
Brick brick1 Status: Connected Total Number of entries: 3 Number of entries in heal pending: 2 Number of entries in split-brain: 1 Number of entries possibly healing: 0