Ceph 20 (“Tentacle”) is the newest Ceph major release, and if you try to add it as RBD primary storage to a CloudStack KVM cluster today, you will very likely hit three separate failures before you get a working setup - none of which is a CloudStack bug. This post walks through all three, and how to get a Tentacle cluster working as CloudStack primary storage today, without downgrading Ceph.

This is a follow-up to Ceph - Deploy Ceph 20 (tentacle) with cephadm-ansible - if you don’t have a Tentacle cluster yet, start there.

Ceph 20 (tentacle) is deployed differently from the older releases I covered before: ceph-ansible is retired, and the cephadm-ansible project only ships a handful of helper playbooks (preflight, ssh key distribution, purge, …) instead of a single site.yml that installs the whole cluster. The actual cluster is built with cephadm itself (cephadm bootstrap + ceph orch ...), and Ansible just prepares the hosts and wires the pieces together. This article walks through deploying a 3-node Ceph 20 cluster on Ubuntu with cephadm-ansible, and the gotchas I hit along the way.

Debian 13 (Trixie) cloud images are official Debian images, pre-installed and customized by the Debian Cloud Team for use with cloud-init on IaaS platforms and generic virtualised environments.

This article introduces how to create Debian 13 cloud images for testing on VMware and XenServer, other than KVM.

CloudStack’s classic KVM guest networking story is “one Linux bridge or OVS bridge per VLAN, per host”. That works, but it doesn’t scale well once you want overlay networks, distributed routing, or anything resembling a modern SDN control plane. OVN (Open Virtual Network) gives you that control plane on top of Open vSwitch: a central Northbound/Southbound database pair plus ovn-controller agents on every hypervisor, all talking Geneve to each other.

This post walks through wiring a small CloudStack KVM setup up to OVN: one dedicated controller node, a handful of Ubuntu KVM hosts, and the small CloudStack-side changes needed to make the Guest network actually land on OVN’s integration bridge instead of a plain OVS bridge.

MySQL and PostgreSQL are two of the most popular open-source relational databases. They share SQL foundations but differ in philosophy, features, and typical use-cases. Below is a concise comparison followed by a handy table of equivalent, commonly-used commands.