KB450419 – Offlining a Ceph Node

Last modified: April 27, 2021
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Offlining a Ceph Node

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 built using Ansible

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:

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