Upgrade a Single-Node Ceph Squid (v19) cephadm Cluster to Tentacle (v20) on Ubuntu 24.04

…and switch from Ubuntu’s apt cephadm (v19) to a manually downloaded cephadm (v20)

This post documents a practical, works-in-real-life upgrade path for a single-node Ceph lab (MON/MGR/OSD/RGW/Dashboard all on one Ubuntu 24.04 host) from Ceph Squid (19.x) to Ceph Tentacle (20.x) using cephadm-managed containers.

It also shows how to switch from Ubuntu’s apt cephadm (19.x) to an upstream, manually downloaded cephadm (20.2.0) after the cluster finishes upgrading.

Lab/test only: a single node provides no redundancy. Warnings like “pools have no replicas configured” are expected.

This post is based on

This upgrade guide assumes you already have the same single-node Squid (v19) cephadm lab from my earlier post:

That post covers: single-node bootstrap on Ubuntu 24.04 (MON/MGR/OSD/RGW/Dashboard), replica=1 pool defaults, and HAProxy + Let’s Encrypt (DNS-01) for S3 (443) and Dashboard (8443).

Target

• Ceph: Tentacle 20.2.0
• OS: Ubuntu 24.04
• Topology: single host (example hostname: ceph)
• Deployment: cephadm (containers)

Why this “mixed tooling” situation happens on Ubuntu 24.04

On Ubuntu 24.04, it’s common that:

• your cluster daemons run as container images (so you can upgrade to Ceph 20.x),
• but the host’s cephadm package from Ubuntu stays on 19.x.

That’s not ideal long-term. After a major upgrade, you should align host-side tooling (cephadm) to the same major release.

1. Single-node requirement: you must have a standby MGR

ceph orch upgrade requires active + standby mgr. On single-host clusters, this is the #1 blocker.

Check current mgr status:

sudo cephadm shell -- ceph mgr stat
sudo cephadm shell -- ceph orch ps --daemon-type mgr

sudo cephadm shell -- ceph mgr stat
sudo cephadm shell -- ceph orch ps --daemon-type mgr

If you see:

• num_standby: 0, or
• applying two mgr fails with Error EINVAL: Cannot place more than one mgr per host

…then you need to allow mgr co-location on a single host.

Allow co-located mgr daemons on a single host

Set this once:

sudo cephadm shell -- ceph config set mgr mgr_standby_modules false
sudo cephadm shell -- ceph config get mgr mgr_standby_modules

sudo cephadm shell -- ceph config set mgr mgr_standby_modules false
sudo cephadm shell -- ceph config get mgr mgr_standby_modules

Expected output: false

Deploy 2 mgr daemons on the same host

Do this inside cephadm shell (avoids confusion about file paths between host and container):

sudo cephadm shell
cat <<'EOF' | ceph orch apply -i -
service_type: mgr
placement:
  hosts:
    - ceph
  count_per_host: 2
EOF
exit

sudo cephadm shell
cat <<'EOF' | ceph orch apply -i -
service_type: mgr
placement:
  hosts:
    - ceph
  count_per_host: 2
EOF
exit

2. Start the upgrade to Tentacle (20.2.0)

Start by version:

sudo cephadm shell -- ceph orch upgrade start --ceph-version 20.2.0

sudo cephadm shell -- ceph orch upgrade start --ceph-version 20.2.0

3. Monitor upgrade progress

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph -s

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph -s

Watch upgrade activity/logs (Ctrl-C is fine; it just stops watching):

sudo cephadm shell -- ceph -W cephadm

sudo cephadm shell -- ceph -W cephadm

4. Single-node caveat: upgrade may stall at the only OSD

On a single-node/single-OSD lab, cephadm safety checks may refuse to stop the only OSD and you’ll see something like:

• Upgrade: unsafe to stop osd(s) at this time (…) PGs are or would become offline

This is expected in a 1-OSD cluster.

Practical lab workaround: redeploy the OSD to the target image

Find the daemon name:

sudo cephadm shell -- ceph orch ps --daemon-type osd

sudo cephadm shell -- ceph orch ps --daemon-type osd

Redeploy it (example osd.0):

sudo cephadm shell -- ceph orch daemon redeploy osd.0 --image quay.io/ceph/ceph:v20.2.0

sudo cephadm shell -- ceph orch daemon redeploy osd.0 --image quay.io/ceph/ceph:v20.2.0

Then re-check:

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions

5. Verify completion

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph -s

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph -s

Expected:

• There are no upgrades in progress currently.
• ceph versions shows 20.2.0 for mon/mgr/osd/rgw
• ceph mgr stat shows num_standby: 1 (two mgr daemons: one active + one standby)

6. Switch Ubuntu apt cephadm (v19) to a manually downloaded cephadm (v20)

Once daemons are fully on Tentacle, update the host-side cephadm tool.

• Protect container runtime packages (optional)

This prevents accidental apt autoremove surprises:

sudo apt-mark manual docker.io containerd runc

sudo apt-mark manual docker.io containerd runc

• Purge Ubuntu’s cephadm

sudo apt purge -y cephadm
sudo apt autoremove --dry-run

sudo apt purge -y cephadm
sudo apt autoremove --dry-run

• Install cephadm 20.2.0 (manual download)

Download and install the Tentacle cephadm binary:

cd /tmp
curl --silent --remote-name --location https://download.ceph.com/rpm-tentacle/el9/noarch/cephadm
chmod +x cephadm
sudo install -m 0755 cephadm /usr/local/sbin/cephadm

cd /tmp
curl --silent --remote-name --location https://download.ceph.com/rpm-tentacle/el9/noarch/cephadm
chmod +x cephadm
sudo install -m 0755 cephadm /usr/local/sbin/cephadm

Verify:

command -v cephadm
cephadm version
sudo cephadm shell -- ceph -s

command -v cephadm
cephadm version
sudo cephadm shell -- ceph -s

Final checklist

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph mgr stat
cephadm version

sudo cephadm shell -- ceph orch upgrade status
sudo cephadm shell -- ceph versions
sudo cephadm shell -- ceph mgr stat
cephadm version

You want:

• no upgrade in progress
• all daemons on 20.2.0
• num_standby: 1
• host cephadm is 20.2.0