About MicroCloud

The MicroCloud snap drives three other snaps (LXD, MicroCeph, and MicroOVN), enabling automated deployment of a highly available LXD cluster for compute with Ceph as the storage driver and OVN as the managed network.

During initialisation, MicroCloud detects the other servers and then prompts you to add disks to Ceph and configure the networking setup.

At the end of this, you’ll have an OVN cluster, a Ceph cluster, and a LXD cluster. LXD itself will have been configured with both networking and storage suitable for use in a cluster.

LXD cluster

MicroCloud sets up a LXD cluster. You can use the microcloud cluster command to show information about the cluster members, or to remove specific members.

Apart from that, you can use LXD commands to manage the cluster. See Clustering in the LXD documentation for more information.

Networking

By default, MicroCloud uses MicroOVN for networking, which is a minimal implementation of OVN (Open Virtual Network). If you decide to not use MicroOVN, MicroCloud falls back on the Ubuntu fan for basic networking.

MicroOVN requires an uplink network that is an actual L2 subnet (which is usually not the case in a virtual cloud environment). In addition, MicroOVN requires its own dedicated network interface, for example, a dedicated physical network interface, a VLAN, or a virtual function on an SR-IOV-capable network interface.

See OVN network in the LXD documentation for more information.

Storage

You have two options for storage in MicroCloud: local storage or distributed storage.

Local storage is faster, but less flexible and not fail-safe. To use local storage, each machine in the cluster requires a local disk. Disk sizes can vary.

For distributed storage, MicroCloud uses MicroCeph, which is a lightweight way of deploying a Ceph cluster. To use distributed storage, you must have at least three disks (attached to at least three different machines).