Removing a Ceph OSD node

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To reduce the capacity of a storage cluster, remove an OSD node.

WARNING: Before removing a Ceph OSD node, ensure that the storage cluster can backfill the contents of all OSDs without reaching the full ratio. Reaching the full ratio will cause the storage cluster to refuse write operations.

Prerequisites

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  • A running IBM Storage Ceph cluster.

  • Root-level access to all nodes in the storage cluster.

Procedure

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  1. Check the storage cluster’s capacity:

    Syntax

    ceph df
rados df
ceph osd df

  2. Temporarily disable scrubbing:

    Syntax

    ceph osd set noscrub
ceph osd set nodeep-scrub

  3. Limit the backfill and recovery features:

    Syntax

    ceph tell DAEMON_TYPE.* injectargs --OPTION_NAME VALUE [--OPTION_NAME VALUE]

    Example

    [ceph: root@host01 /]# ceph tell osd.* injectargs --osd-max-backfills 1 --osd-recovery-max-active 1 --osd-recovery-op-priority 1

  4. Remove each OSD on the node from the storage cluster:

    • IMPORTANT: When removing an OSD node from the storage cluster, IBM recommends removing one OSD at a time within the node and allowing the cluster to recover to an active+clean state before proceeding to remove the next OSD.

      1. After you remove an OSD, check to verify that the storage cluster is not getting to the near-full ratio:

        Syntax

        ceph -s
ceph df

      2. Repeat this step until all OSDs on the node are removed from the storage cluster.

  5. Once all OSDs are removed, remove the host: