User:Aranzinger/Spielwiese13

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The .mgr pool in Ceph safes meta data for the Ceph manager daemon (ceph-mgr) that are required for the supervision and the management of the cluster. In the event of mistakes within the manager, it is possible to restart the pool. This article is a short instruction for the recreation of the .mgr- pool.

Description of problem

It may occur that there are error messages regarding the .mgr pool within Proxmox Ceph HCI. For example, the following mistake can appear:

pg 1.0 num got status unknown

Recreation of .mgr pools

Hint: The .mgr-pool for Proxmox systems with Ceph 16.X or older is called different: device_health_metrics!

The pool has to be restarted to fix the error. To find out which pool belongs to which placement group, you can execute the following command:

root@pve-b11:~# ceph osd lspools
1 .mgr
5 vm_nvme
6 cephfs_data
7 cephfs_metadata

The Placement Group 1 is also assigned to the .mgr-pool. The .mgr-pool can be recreated without effects.

The procedure is as follows:

  1. delete MGR pool under Host / Ceph / Pool
  2. delete the active manager service under Host -> Ceph -> Monitor
  3. wait until a standby manager service is active, only then the old deleted MGR service entry will disappear
  4. recreate the manager service that has just been deleted on the respective host

Now, a new .mgr-pool has been created, which is fully functional.

Author: Jonas Sterr

Jonas Sterr has been working for Thomas-Krenn for several years. Originally employed as a trainee in technical support and then in hosting (formerly Filoo), Mr. Sterr now mainly deals with the topics of storage (SDS / Huawei / Netapp), virtualization (VMware, Proxmox, HyperV) and network (switches, firewalls) in product management at Thomas-Krenn.AG in Freyung.