From d3c2d786251b10c3299709abb0341d0b6ebf22c8 Mon Sep 17 00:00:00 2001
From: Ben Vincent <ben@unkin.net>
Date: Sat, 17 Jan 2026 13:15:22 +1100
Subject: [PATCH] chore: docs for ceph

- add maintenance mode, how to bootstrap an osd, remove an osd
---
 doc/ceph/README.md | 75 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/doc/ceph/README.md b/doc/ceph/README.md
index 8d211e2..276f8b1 100644
--- a/doc/ceph/README.md
+++ b/doc/ceph/README.md
@@ -58,3 +58,78 @@ this will overwrite the current capabilities of a given client.user
       mon 'allow r' \
       mds 'allow rw path=/' \
       osd 'allow rw pool=media_data'
+
+## adding a new osd on new node
+
+create the ceph conf (automate this?)
+
+    cat <<EOF | sudo tee /etc/ceph/ceph.conf
+    [global]
+      auth_client_required = cephx
+      auth_cluster_required = cephx
+      auth_service_required = cephx
+      fsid = de96a98f-3d23-465a-a899-86d3d67edab8
+      mon_allow_pool_delete = true
+      mon_initial_members = prodnxsr0009,prodnxsr0010,prodnxsr0011,prodnxsr0012,prodnxsr0013
+      mon_host = 198.18.23.9,198.18.23.10,198.18.23.11,198.18.23.12,198.18.23.13
+      ms_bind_ipv4 = true
+      ms_bind_ipv6 = false
+      osd_crush_chooseleaf_type = 1
+      osd_pool_default_min_size = 2
+      osd_pool_default_size = 3
+      osd_pool_default_pg_num = 128
+      public_network = 198.18.23.1/32,198.18.23.2/32,198.18.23.3/32,198.18.23.4/32,198.18.23.5/32,198.18.23.6/32,198.18.23.7/32,198.18.23.8/32,198.18.23.9/32,198.18.23.10/32,198.18.23.11/32,198.18.23.12/32,198.18.23.13/32
+    EOF
+
+ssh to one of the monitor hosts, then transfer the keys required
+
+    sudo cat /etc/ceph/ceph.client.admin.keyring | ssh prodnxsr0003 'sudo tee /etc/ceph/ceph.client.admin.keyring'
+    sudo cat /var/lib/ceph/bootstrap-osd/ceph.keyring | ssh prodnxsr0003 'sudo tee /var/lib/ceph/bootstrap-osd/ceph.keyring'
+
+assuming we are adding /dev/sda to the cluster, first zap the disk to remove partitions/lvm/metadata
+
+    sudo ceph-volume lvm zap /dev/sda --destroy
+
+then add it to the cluster
+
+    sudo ceph-volume lvm create --data /dev/sda
+
+## removing an osd
+
+check what OSD IDs were on this host (if you know it)
+
+    sudo ceph osd tree
+
+or check for any DOWN osds
+
+    sudo ceph osd stat
+    sudo ceph health detail
+
+once you identify the old OSD ID, remove it with these steps, replace X with the actual OSD ID:
+
+    sudo ceph osd out osd.X
+    sudo ceph osd down osd.X
+    sudo ceph osd crush remove osd.X
+    sudo ceph auth del osd.X
+    sudo ceph osd rm osd.X
+
+
+## maintenance mode for the cluster
+
+from one node in the cluster disable recovery
+
+    sudo ceph osd set noout
+    sudo ceph osd set nobackfill
+    sudo ceph osd set norecover
+    sudo ceph osd set norebalance
+    sudo ceph osd set nodown
+    sudo ceph osd set pause
+
+to undo the change, use unset
+
+    sudo ceph osd unset noout
+    sudo ceph osd unset nobackfill
+    sudo ceph osd unset norecover
+    sudo ceph osd unset norebalance
+    sudo ceph osd unset nodown
+    sudo ceph osd unset pause