tasks/vm-ceph-bootstrap/instruction.md

You are a Ceph storage administrator. Deploy a Ceph cluster and configure block storage on the following infrastructure.

══════════════════════════════════════════════════════════════════ ENVIRONMENT ══════════════════════════════════════════════════════════════════ Nodes: node0 through node6 (7-node KVM cluster on a private libvirt network)

You are currently on node0. From node0 you have passwordless root SSH to every other node by short name: ssh root@node1 ... ssh root@node6

/etc/hosts and /etc/syscraft/cluster-info are populated on every node with the mapping <short-name>=<ip>. Use those for any IP lookups.

Network: Single private subnet 192.168.100.0/24 on the only NIC of each VM. Look up node0's private IP for --mon-ip: awk -F= '/^node0=/{print $2}' /etc/syscraft/cluster-info Do NOT pass --cluster-network — this deployment uses a single network.

Storage: Each node has TWO unused raw block devices for OSDs: /dev/loop0 (30 GiB) /dev/loop1 (30 GiB) The root filesystem is on /dev/vda — do not touch it. The loop devices are attached automatically at boot by a systemd unit; if they are missing on a worker for any reason, losetup -f --show /var/lib/cephbench/disk_b.img (and disk_c.img) will recreate them.

OS: Ubuntu 24.04 LTS on all nodes.

Container runtime: podman is installed on all nodes.

Pre-installed tooling (ready to use, no installation needed): cephadm (Ceph Squid, v19.x) — available on all nodes via /usr/sbin/cephadm podman, lvm2, xfsprogs, chrony, jq — installed on all nodes

Pre-pulled image: quay.io/ceph/ceph:v19.2.0 (Ceph Squid) This image is already cached in podman on every node. --image is a GLOBAL flag that comes BEFORE the subcommand: cephadm --image quay.io/ceph/ceph:v19.2.0 bootstrap ... NOT: cephadm bootstrap --image ... (this will fail)

Node hostnames may be FQDN-shaped. Pass --allow-fqdn-hostname to cephadm bootstrap.

When adding hosts to the cluster, the short name must match the actual hostname on that node. The nodes' short names are node0..node6. Correct usage: ceph orch host add node1 <node1-ip-from-cluster-info> (short name first, then IP as the address)

This is a 7-node cluster — do NOT pass --single-host-defaults.

══════════════════════════════════════════════════════════════════ TASKS (all must be completed) ══════════════════════════════════════════════════════════════════

1. Bootstrap a Ceph cluster using cephadm on node0.

2. Join node1 through node6 into the cluster.

3. Add all available data disks (/dev/loop0 and /dev/loop1 on each node) as OSDs.

4. Create a replicated storage pool named "data_rep" with 3 replicas and application=rbd.

5. Create an erasure-coded storage pool named "data_ec" using:

   • Algorithm: reed_sol_van (jerasure plugin)
   • k=4, m=2
   • Failure domain: host

6. In the data_rep pool, create a 100 GiB RBD block device image named "bench_image". Map it to a local block device on node0, format it with xfs, and mount it at /mnt/ceph_data.

══════════════════════════════════════════════════════════════════ SCORING ══════════════════════════════════════════════════════════════════ 5 pts — Ceph cluster is reachable (bootstrap succeeded) 15 pts — Cluster health is HEALTH_OK 15 pts — data_rep pool: 3 replicas, type=replicated, application=rbd 15 pts — data_ec pool: k=4 m=2 reed_sol_van jerasure host failure domain 20 pts — bench_image exists in data_rep, size ~100 GiB 20 pts — /mnt/ceph_data is mounted 10 pts — data can be written to /mnt/ceph_data