KB450419 – Offlining a Ceph Node

Last modified: July 26, 2021
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Scope/Description

  • This article will walk you through taking a Ceph node offline safely and then online it and bring the cluster back safely.

Prerequisites

  • A Ceph Cluster.
  • SSH Access to a Ceph Node.

Steps:

  • SSH into the node you want to take down
  • Run these 3 commands to set flags on the cluster to prepare for offlining a node.

root@osd1:~# ceph osd set noout

root@osd1:~# ceph osd set norebalance

root@osd1:~# ceph osd set norecover
  • Run ceph -s to see the cluster is in a warning state and that the 3 flags have been set.

root@osd1:~# ceph -s
  • Run shutdown now on the node you wish to turn off.
root@osd1:~# shutdown now
  • Once the system is back up and running and joined to the cluster unset the 3 flags we previously set.

root@osd1:~# ceph osd unset noout
root@osd1:~# ceph osd unset norebalance
root@osd1:~# ceph osd unset norecover
  • Running ceph -s again to show a healthy state and to confirm the flags are unset.

root@osd1:~# ceph -s

Verification

  • A ceph -s shows a healthy state and shows all nodes online.

Troubleshooting

  • Ensure you are on a Ceph node that has permission to do Ceph commands.
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