Removing a Node

Scenario

Removing a node from a cluster will re-install the node OS and clear CCE components on the node.

Removing a node will not delete the server corresponding to the node. You are advised to remove nodes at off-peak hours to avoid impacts on your services.

After a node is removed from the cluster, the node is still running.

Constraints

• Nodes can be removed only when the cluster is in the Available or Unavailable status.
• A CCE node can be removed only when it is in the Active, Abnormal, or Error status.
• A CCE node in the Active status can have its OS re-installed and CCE components cleared after it is removed.
• If the OS fails to be re-installed after the node is removed, manually re-install the OS. After the re-installation, log in to the node and run the clearance script to clear CCE components. For details, see Handling Failed OS Reinstallation.
• Removing a node will cause PVC/PV data loss for the local PV associated with the node. These PVCs and PVs cannot be restored or used again. In this scenario, the pod that uses the local PV is evicted from the node. A new pod is created and stays in the pending state. This is because the PVC used by the pod has a node label, due to which the pod cannot be scheduled.

Precautions

• Removing a node will lead to pod migration, which may affect services. Perform this operation during off-peak hours.
• Unexpected risks may occur during the operation. Back up data in advance.
• While the node is being deleted, the backend will set the node to the unschedulable state.
• After you remove the node and re-install the OS, the original LVM partitions will be cleared and the data managed by LVM will be cleared. Therefore, back up data in advance.

Procedure

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. In the navigation pane, choose Nodes. On the displayed page, click the Nodes tab.
3. Locate the target node and choose More > Remove in the Operation column.
4. In the dialog box displayed, configure the login information required for re-installing the OS and click Yes. Wait until the node is removed.

   After the node is removed, workload pods on the node are automatically migrated to other available nodes.

Handling Failed OS Reinstallation

You can perform the following steps to re-install the OS and clear the CCE components on the node if previous attempts fail:

1. Log in to the management console of the server and re-install the OS.
2. Log in to the server and run the following commands to clear the CCE components and LVM data:

   Write the following scripts to the clean.sh file:

   lsblk
   vgs --noheadings | awk '{print $1}' | xargs vgremove -f
   pvs --noheadings | awk '{print $1}' | xargs pvremove -f
   lvs --noheadings | awk '{print $1}' | xargs -i lvremove -f --select {}
   function init_data_disk() {
       all_devices=$(lsblk -o KNAME,TYPE | grep disk | grep -v nvme | awk '{print $1}' | awk '{ print "/dev/"$1}')
       for device in ${all_devices[@]}; do
           isRootDisk=$(lsblk -o KNAME,MOUNTPOINT $device 2>/dev/null| grep -E '[[:space:]]/$' | wc -l )
           if [[ ${isRootDisk} != 0 ]]; then
               continue
           fi
           dd if=/dev/urandom of=${device} bs=512 count=64
           return
       done
       exit 1
   }
   init_data_disk
   lsblk

   Run the following command:

   bash clean.sh