Ceph Reef : OSD を追加/削除する2025/10/28

既存の Ceph クラスターに OSD を追加/削除するには、以下のように設定します。

                                         |
        +--------------------+           |           +----------------------+
        |   [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]	例として、管理ノードから [node04] ノードに、新たに OSD を追加します。 [node04] ノード上で Ceph 用に設定するブロックデバイスは [/dev/sdb] を使用します。

# 公開鍵転送

node01:~ #

ssh-copy-id node04

# Firewalld 稼働中の場合はサービス許可

node01:~ #

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

# 必要なパッケージをインストール

node01:~ #

ssh node04 "zypper -n install ceph"

# 必要なファイルを転送

node01:~ #

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

node01:~ #

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

node01:~ #

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

# OSD の設定

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

ssh node04 \
"chown -R ceph:ceph /etc/ceph/ceph.* /var/lib/ceph; \
parted --script /dev/sdb 'mklabel gpt'; \
parted --script /dev/sdb "mkpart primary 0% 100%"; \
ceph-volume 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 13108d1a-4b5f-43b4-8374-7d68e2fdf0b4
Running command: vgcreate --force --yes ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b /dev/sdb1
 stdout: Physical volume "/dev/sdb1" successfully created.
  Creating devices file /etc/lvm/devices/system.devices
 stdout: Volume group "ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b" successfully created
Running command: lvcreate --yes -l 40959 -n osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4 ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b
 stdout: Logical volume "osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4" created.
Running command: /usr/bin/ceph-authtool --gen-print-key
Running command: /usr/bin/mount -t tmpfs tmpfs /var/lib/ceph/osd/ceph-3
Running command: /sbin/restorecon /var/lib/ceph/osd/ceph-3
Running command: /usr/bin/chown -h ceph:ceph /dev/ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b/osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4
Running command: /usr/bin/chown -R ceph:ceph /dev/dm-0
Running command: /usr/bin/ln -s /dev/ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b/osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4 /var/lib/ceph/osd/ceph-3/block
Running command: /usr/bin/ceph --cluster ceph --name client.bootstrap-osd --keyring /var/lib/ceph/bootstrap-osd/ceph.keyring mon getmap -o /var/lib/ceph/osd/ceph-3/activate.monmap
 stderr: got monmap epoch 2
--> Creating keyring file for osd.3
Running command: /usr/bin/chown -R ceph:ceph /var/lib/ceph/osd/ceph-3/keyring
Running command: /usr/bin/chown -R ceph:ceph /var/lib/ceph/osd/ceph-3/
Running command: /usr/bin/ceph-osd --cluster ceph --osd-objectstore bluestore --mkfs -i 3 --monmap /var/lib/ceph/osd/ceph-3/activate.monmap --keyfile - --osd-data /var/lib/ceph/osd/ceph-3/ --osd-uuid 13108d1a-4b5f-43b4-8374-7d68e2fdf0b4 --setuser ceph --setgroup ceph
 stderr: 2025-10-28T12:46:01.661+0900 7f16e91a8600 -1 bluestore(/var/lib/ceph/osd/ceph-3//block) _read_bdev_label unable to decode label at offset 102: void bluestore_bdev_label_t::decode(ceph::buffer::v15_2_0::list::const_iterator&) decode past end of struct encoding: Malformed input [buffer:3]
 stderr: 2025-10-28T12:46:01.662+0900 7f16e91a8600 -1 bluestore(/var/lib/ceph/osd/ceph-3//block) _read_bdev_label unable to decode label at offset 102: void bluestore_bdev_label_t::decode(ceph::buffer::v15_2_0::list::const_iterator&) decode past end of struct encoding: Malformed input [buffer:3]
 stderr: 2025-10-28T12:46:01.662+0900 7f16e91a8600 -1 bluestore(/var/lib/ceph/osd/ceph-3//block) _read_bdev_label unable to decode label at offset 102: void bluestore_bdev_label_t::decode(ceph::buffer::v15_2_0::list::const_iterator&) decode past end of struct encoding: Malformed input [buffer:3]
 stderr: 2025-10-28T12:46:01.662+0900 7f16e91a8600 -1 bluestore(/var/lib/ceph/osd/ceph-3/) _read_fsid unparsable uuid
--> ceph-volume lvm prepare successful for: /dev/sdb1
Running command: /usr/bin/chown -R ceph:ceph /var/lib/ceph/osd/ceph-3
Running command: /usr/bin/ceph-bluestore-tool --cluster=ceph prime-osd-dir --dev /dev/ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b/osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4 --path /var/lib/ceph/osd/ceph-3 --no-mon-config
Running command: /usr/bin/ln -snf /dev/ceph-df89d4b2-2824-4bd3-bcdf-77d4267fcf1b/osd-block-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4 /var/lib/ceph/osd/ceph-3/block
Running command: /usr/bin/chown -h ceph:ceph /var/lib/ceph/osd/ceph-3/block
Running command: /usr/bin/chown -R ceph:ceph /dev/dm-0
Running command: /usr/bin/chown -R ceph:ceph /var/lib/ceph/osd/ceph-3
Running command: /usr/bin/systemctl enable ceph-volume@lvm-3-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4
 stderr: Created symlink '/etc/systemd/system/multi-user.target.wants/ceph-volume@lvm-3-13108d1a-4b5f-43b4-8374-7d68e2fdf0b4.service' → '/usr/lib/systemd/system/ceph-volume@.service'.
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
vm create --data /dev/sdb1" 

node01:~ # ceph -s 
  cluster:
    id:     a1598936-342f-40c2-babf-f4b61a9e0bf2
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 3h)
    mgr: node01(active, since 2h)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 56s), 4 in (since 65s)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   8 pools, 321 pgs
    objects: 220 objects, 491 KiB
    usage:   277 MiB used, 640 GiB / 640 GiB avail
    pgs:     321 active+clean

  io:
    client:   36 KiB/s rd, 0 B/s wr, 35 op/s rd, 23 op/s wr

[2]	既存のクラスターから OSD を削除する場合は以下のように実行します。例として、管理ノードから [node04] ノードを削除します。

node01:~ #

ceph -s

  cluster:
    id:     a1598936-342f-40c2-babf-f4b61a9e0bf2
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 3h)
    mgr: node01(active, since 2h)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 102s), 4 in (since 111s)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   8 pools, 321 pgs
    objects: 220 objects, 491 KiB
    usage:   277 MiB used, 640 GiB / 640 GiB avail
    pgs:     321 active+clean

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

# 削除したい OSD の ID を指定してクラスターから分離する

node01:~ #

ceph osd out 3

marked out osd.3.

# クラスターステータスをリアルタイムウォッチする
# [ceph osd out ***] 実行後、リバランスが実行されデータが再配置される
# リアルタイムウォッチを終了する場合は [Ctrl + c]

node01:~ #

ceph -w

  cluster:
    id:     a1598936-342f-40c2-babf-f4b61a9e0bf2
    health: HEALTH_WARN
            Reduced data availability: 27 pgs inactive, 67 pgs peering
            too many PGs per OSD (321 > max 250)

  services:
    mon: 1 daemons, quorum node01 (age 105s)
    mgr: node01(active, since 2h)
    mds: 1/1 daemons up
    osd: 4 osds: 4 up (since 9m), 3 in (since 4s)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    volumes: 1/1 healthy
    pools:   8 pools, 321 pgs
    objects: 221 objects, 491 KiB
    usage:   227 MiB used, 480 GiB / 480 GiB avail
    pgs:     1.246% pgs unknown
             28.349% pgs not active
             226 active+clean
             91  peering
             4   unknown

  io:
    client:   2.0 KiB/s rd, 0 B/s wr, 1 op/s rd, 0 op/s wr
.....
.....

# クラスターステータスが [HEALTH_OK] になったのち、対象ノードの OSD サービスを無効化

node01:~ #

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

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

# 対象ノードの OSD ID を指定してクラスターから削除する

node01:~ #

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

purged osd.3

node01:~ #

ceph -s

  cluster:
    id:     a1598936-342f-40c2-babf-f4b61a9e0bf2
    health: HEALTH_OK

  services:
    mon: 1 daemons, quorum node01 (age 3m)
    mgr: node01(active, since 2h)
    osd: 3 osds: 3 up (since 39s), 3 in (since 2m)
    rgw: 1 daemon active (1 hosts, 1 zones)

  data:
    pools:   6 pools, 161 pgs
    objects: 196 objects, 454 KiB
    usage:   208 MiB used, 480 GiB / 480 GiB avail
    pgs:     161 active+clean