Ceph Quincy : Add or Remove OSDs2022/06/14

This is how to add or remove OSDs from exisiting Cluster.

                                         |
        +--------------------+           |           +----------------------+
        |   [dlp.srv.world]  |10.0.0.30  |  10.0.0.31|    [www.srv.world]   |
        |     Ceph Client    +-----------+-----------+        RADOSGW       |
        |                    |           |           |                      |
        +--------------------+           |           +----------------------+
            +----------------------------+----------------------------+
            |                            |                            |
            |10.0.0.51                   |10.0.0.52                   |10.0.0.53 
+-----------+-----------+    +-----------+-----------+    +-----------+-----------+
|   [node01.srv.world]  |    |   [node02.srv.world]  |    |   [node03.srv.world]  |
|     Object Storage    +----+     Object Storage    +----+     Object Storage    |
|     Monitor Daemon    |    |                       |    |                       |
|     Manager Daemon    |    |                       |    |                       |
+-----------------------+    +-----------------------+    +-----------------------+

[1]	For example, Add a [node04] node for OSD on Admin Node. For Block device on new [node04] Node, use [/dev/sdb] on this example.

# transfer public key

[root@node01 ~]#

ssh-copy-id node04

# if Firewalld is running, allow service

[root@node01 ~]#

ssh node04 "firewall-cmd --add-service=ceph; firewall-cmd --runtime-to-permanent"

# install required packages

[root@node01 ~]#

ssh node04 "dnf -y install centos-release-ceph-quincy epel-release; dnf -y install ceph"

# transfer required files

[root@node01 ~]#

scp /etc/ceph/ceph.conf node04:/etc/ceph/ceph.conf

[root@node01 ~]#

scp /etc/ceph/ceph.client.admin.keyring node04:/etc/ceph

[root@node01 ~]#

scp /var/lib/ceph/bootstrap-osd/ceph.keyring node04:/var/lib/ceph/bootstrap-osd

# configure OSD

[root@node01 ~]# ssh node04 \
"chown ceph. /etc/ceph/ceph.* /var/lib/ceph/bootstrap-osd/*; \
parted --script /dev/sdb 'mklabel gpt'; \
parted --script /dev/sdb "mkpart primary 0% 100%"; \
ceph-volume lvm create --data /dev/sdb1" 

Running command: /usr/bin/ceph-authtool --gen-print-key
Running command: /usr/bin/ceph --cluster ceph --name client.bootstrap-osd --keyring /var/lib/ceph/bootstrap-osd/ceph.keyring -i - osd new 6de3f781-8332-4e35-8736-75cf1f2c1953
Running command: vgcreate --force --yes ceph-b6f32fdf-be73-4679-ad71-0a457e8ca479 /dev/sdb1
 stdout: Physical volume "/dev/sdb1" successfully created.
 stdout: Volume group "ceph-b6f32fdf-be73-4679-ad71-0a457e8ca479" successfully created
Running command: lvcreate --yes -l 40959 -n osd-block-6de3f781-8332-4e35-8736-75cf1f2c1953 ceph-b6f32fdf-be73-4679-ad71-0a457e8ca479

.....
.....

Running command: /usr/bin/systemctl enable --runtime ceph-osd@3
 stderr: Created symlink /run/systemd/system/ceph-osd.target.wants/ceph-osd@3.service → /usr/lib/systemd/system/ceph-osd@.service.
Running command: /usr/bin/systemctl start ceph-osd@3
--> ceph-volume lvm activate successful for osd ID: 3
--> ceph-volume lvm create successful for: /dev/sdb1

[root@node01 ~]# ceph -s 
  cluster:
    id:     8df33401-6131-4c08-9ceb-3894ab029257
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 5h)
    mgr: node01(active, since 41m)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 3m), 4 in (since 4m)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   7 pools, 209 pgs
    objects: 217 objects, 466 KiB
    usage:   204 MiB used, 640 GiB / 640 GiB avail
    pgs:     209 active+clean

[2]	To remove an OSD Node from existing Cluster, run commands like follows. For example, Remove [node04] node.

[root@node01 ~]#

ceph -s

  cluster:
    id:     8df33401-6131-4c08-9ceb-3894ab029257
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 5h)
    mgr: node01(active, since 42m)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 4m), 4 in (since 5m)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   7 pools, 209 pgs
    objects: 217 objects, 466 KiB
    usage:   205 MiB used, 640 GiB / 640 GiB avail
    pgs:     209 active+clean

[root@node01 ~]#

ceph osd tree

ID  CLASS  WEIGHT   TYPE NAME        STATUS  REWEIGHT  PRI-AFF
-1         0.62476  root default
-3         0.15619      host node01
 0    hdd  0.15619          osd.0        up   1.00000  1.00000
-5         0.15619      host node02
 1    hdd  0.15619          osd.1        up   1.00000  1.00000
-7         0.15619      host node03
 2    hdd  0.15619          osd.2        up   1.00000  1.00000
-9         0.15619      host node04
 3    hdd  0.15619          osd.3        up   1.00000  1.00000

# specify OSD ID of a node you'd like to remove

[root@node01 ~]#

ceph osd out 3

marked out osd.3.

# live watch cluster status
# after running [ceph osd out ***], rebalancing is executed automatically
# to quit live watch, push [Ctrl + c]

[root@node01 ~]#

ceph -w

  cluster:
    id:     8df33401-6131-4c08-9ceb-3894ab029257
    health: HEALTH_WARN
            Reduced data availability: 1 pg inactive
            Degraded data redundancy: 45/651 objects degraded (6.912%), 23 pgs degraded

  services:
    mon: 1 daemons, quorum node01 (age 5h)
    mgr: node01(active, since 43m)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 5m), 3 in (since 12s); 40 remapped pgs
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   7 pools, 209 pgs
    objects: 217 objects, 466 KiB
    usage:   173 MiB used, 480 GiB / 480 GiB avail
    pgs:     4.306% pgs not active
             45/651 objects degraded (6.912%)
             134/651 objects misplaced (20.584%)
             163 active+clean
             17  active+recovering+undersized+degraded+remapped
             9   active+remapped+backfilling
             5   active+recovering
             4   activating+undersized+degraded+remapped
             3   activating+undersized+remapped
             3   active+recovering+undersized+remapped
             2   active+recovery_wait+undersized+degraded+remapped
             1   activating
             1   activating+remapped
             1   active+remapped+backfill_wait

  io:
    recovery: 0 B/s, 0 objects/s


2022-06-14T14:35:14.828371+0900 mon.node01 [INF] Health check cleared: PG_AVAILABILITY (was: Reduced data availability: 1 pg inactive)
.....
.....

# after status turns to [HEALTH_OK], disable OSD service on the target node

[root@node01 ~]#

ssh node04 "systemctl disable --now ceph-osd@3.service"

Removed /run/systemd/system/ceph-osd.target.wants/ceph-osd@3.service.

# remove the node to specify target OSD ID

[root@node01 ~]#

ceph osd purge 3 --yes-i-really-mean-it

purged osd.3

[root@node01 ~]#

ceph -s

  cluster:
    id:     8df33401-6131-4c08-9ceb-3894ab029257
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 5h)
    mgr: node01(active, since 47m)
    mds: 1/1 daemons up
    osd: 3 osds: 3 up (since 10s), 3 in (since 4m)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   7 pools, 209 pgs
    objects: 217 objects, 466 KiB
    usage:   194 MiB used, 480 GiB / 480 GiB avail
    pgs:     209 active+clean

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