Add Ceph capacity safely

This runbook covers Add Ceph capacity safely on a Ceph Tentacle cluster.

When to use

• Active production scenario matching the impact (service-affecting)
• The prerequisites are met

Prerequisites

Before starting this runbook, verify each prerequisite has been met. If a prerequisite is not met, resolve it first or escalate.

• A pool is at or near nearfull
• Capacity needs to be added

Pre-checks

Collect evidence before taking action. Evidence is the proof the runbook worked.

# ceph -s reports the cluster is HEALTH_OK
# The new disks are verified healthy
# The new host meets the prerequisites
# A maintenance window is scheduled if needed

Procedure

Step 1

Decide the addition: OSDs on existing host vs new host

Step 2

For new OSDs on an existing host: ceph orch daemon add osd <host>

Step 3

For a new host: ceph orch host add <hostname>; deploy OSDs

Step 4

Verify the new OSDs come up: ceph osd tree

Step 5

Wait for backfill: ceph progress

Step 6

Verify capacity headroom is restored: ceph df

Verification

After completing the procedure, verify the result:

# ceph -s reports HEALTH_OK
# Backfill completes
# Pool utilisation is below nearfull
# ceph df shows the expected usable capacity

Rollback

If the procedure does not produce the expected verification, roll back:

• If OSDs do not deploy: check the device and the host
• If backfill is slow: tune recovery settings
• If a new OSD produces SMART errors: replace the disk

Escalation

If you cannot roll back or the rollback fails, escalate:

• Storage team