Adding OSD hosts in stretch mode

You can add Ceph OSDs in the stretch mode. The procedure is similar to the addition of the OSD hosts on a cluster where stretch mode is not enabled.

Before you begin

Before you begin, make sure that you have the following prerequisites in place:
  • A running IBM Storage Ceph cluster.
  • Stretch mode is enabled on a cluster.
  • Root-level access to the nodes.

Procedure

  1. List the available devices to deploy OSDs. 
    ceph orch device ls [--hostname=HOST_1 HOST_2] [--wide] [--refresh]
    For example, 
    [ceph: root@host01 /]# ceph orch device ls
  2. Deploy the OSDs on specific hosts or on all the available devices.
    • Create an OSD from a specific device on a specific host. 
      ceph orch daemon add osd HOST:DEVICE_PATH
      For example, 
      [ceph: root@host01 /]# ceph orch daemon add osd host03:/dev/sdb
    • Deploy OSDs on any available and unused devices.
      Important: This command creates collocated WAL and DB devices. Do not use this command to create non-collocated devices.
      ceph orch apply osd --all-available-devices
  3. Move the OSD hosts under the CRUSH bucket. 
    ceph osd crush move HOST datacenter=DATACENTER
    Note: Ensure you add the same topology nodes on both sites. Issues can occur if hosts are added only on one site.
    For example, 
    [ceph: root@host01 /]# ceph osd crush move host03 datacenter=DC1
 [ceph: root@host01 /]# ceph osd crush move host06 datacenter=DC2

What to do next

Verify that the OSD hosts and OSDs are added in the CRUSH bucket, by using the ceph osd tree command.