Draining a node

About this task

Drain a node using the Drain option in OpsCenter Nodes administration. Draining a node flushes all memtables from the node to SSTables on disk. Restarting DSE after draining a node is required for the node to start accepting writes again. Typically, a node is drained before upgrading to a new version of DSE.

For information about manually draining a node, see the corresponding nodetool drain command.

Draining a node is not necessary with either the OpsCenter UI or the drain nodetool command when upgrading a node to a minor DSE version using LCM.

To simply flush memtables to disk, use the Flush option in OpsCenter or the corresponding nodetool flush command.

Prerequisites

If OpsCenter role-based security is enabled, be sure that the permission for the Drain option in Node Operations is enabled for the appropriate user roles.

Procedure

  1. Click cluster name > Nodes.

  2. In the Ring or List view, select the node.

    The Node Details dialog appears.

  3. From the Actions menu, click Drain..

    Drain option Node Details Actions menu

    The Drain Node dialog prompts you to confirm the operation.

    opscConfirmNodeDrain

  4. Click Drain Node.

  5. When the drain operations completes, perform the operation that required draining the node, such as upgrading a node manually.

  6. Click Restart from the Node Actions menu.

    The node cannot accept writes until DSE is restarted.

    The Restart DSE dialog appears.

    opscRestartDSE

  7. Click Restart DSE. It is not necessary to select the Drain before stopping option again.