How to remove/add OSD from Ceph cluster

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  1. Remove OSD from Ceph Cluster

Firstly check which OSD is down and want to remove from Ceph Cluster by using given command: ceph osd tree . Let’s say it is osd.20 which is down and want to remove. Now use the following commands

a. ceph osd out osd.20 (If you see “osd.20 is already out” — it’s ok.)

b. ceph osd down osd.20

c. Remove it: ceph osd rm osd.20If it says ‘Error EBUSY: osd.11 is still up; must be down before removal.’ that means OSD is not dead yet. Go to the host it resides on and kill it (systemctl stop ceph-osd@20), and repeat rm operation.

d. ceph osd crush rm osd.20

e. remove it authorization (it should prevent problems with ‘couldn’t add new osd with same number’): ceph auth del osd.20.

f. Make sure it is safe to destroy the OSD:

ceph osd destroy 20 --yes-i-really-mean-it

g. Now check with the following command: ceph -s or ceph -w

h. If want to remove ceph LVM volume created on host machine (suppose lvm created on sdb) so use given command :

To find ceph volume group name : lvs

To remove Logical Volume : lvremove <ceph-VG-name>

2. Add OSD on Ceph Cluster

a. Ceph cluster required ceph volume and it will auto generate the osd number (also required ceph-osd package on host machine apt install ceph-osd). So following command needed to add OSD

b. Zap a disk for the new OSD: ceph-volume lvm zap /dev/sdb

c. batch Creates OSDs from a list of devices using a filestore or bluestore (default) setup: ceph-volume lvm batch --bluestore /dev/sdb

d. ceph-volume lvm activate --all

e. Now OSD has been added . Check using: systemctl status ceph-osd@20

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