Reference¶
The reference material in this section provides technical descriptions of MicroCloud.
Requirements¶
Hardware requirements¶
MicroCloud supports up to 50 machines as members of the same cluster.
For testing and development, a single machine (physical or virtual) can be used to create a cluster.
For production environments, a minimum of 3 physical machines is required as cluster members. We do not recommend using virtual machines as cluster members in production.
For critical deployments, we recommend a minimum of 4 cluster members. While 3 members are sufficient for high availability, an extra member provides redundancy for running critical applications.
Tip
If you want to add further members to a cluster after initialization, use the microcloud add command.
You can mix different processor architectures within the same MicroCloud cluster.
Each cluster member must have at least 8 GiB of RAM (more depending on the connected disks). We recommend at least 32 GiB of RAM for production environments.
Storage requirements¶
All storage disks should be free of existing partitions or file systems.
Also see Ceph’s hardware recommendations.
Local storage¶
Local storage is typically sufficient for testing and development, as it is fast and convenient. To use local storage, each cluster member requires a local disk.
Distributed storage¶
You can set up distributed storage on a test cluster with a single member, but it won’t have the recommended replication configuration which ensures high availability.
High availability¶
For high availability, and the ability to recover a cluster should something go wrong, use distributed storage with at least three additional disks for use by Ceph. These disks must be on at least three different cluster members.
Production environments¶
For production environments, we recommend at least 3 NVMe disks per cluster member:
1 for OS
1 for local storage
1 for distributed storage
Full disk encryption¶
If you intend to use full disk encryption on any cluster member, the dm-crypt kernel module must be available, and the snap dm-crypt plug must be connected to MicroCeph. The dm-crypt module is available by default in Ubuntu 24.04 and higher.
For further information, see the Prerequisites section of this page: Full disk encryption. Note that the command shown on that page to connect the snap dm-crypt plug can only be performed once MicroCeph is installed. The MicroCloud installation steps include installing MicroCeph; thus, install MicroCloud first, then connect the plug.
Networking requirements¶
Required network interfaces¶
For networking, each machine in the MicroCloud cluster requires at least two dedicated network interfaces: one for intra-cluster communication and one for external connectivity. These can be connected to the same network, or different networks.
In production environments, we recommend dual-port network cards with a minimum 10 GiB capacity, or higher if low latency is essential.
- Network interface for intra-cluster traffic
MicroCloud requires one network interface that is pre-configured with an IP address that is within the same subnet as the IPs of the other cluster members. The network that it is connected to must support multicast.
This network interface can be, for example, a dedicated physical network interface, a VLAN, or a virtual function on an SR-IOV-capable network interface. It serves as the dedicated network interface for MicroCloud and is used for multicast discovery (during setup) and all internal traffic between the MicroCloud, OVN, and Ceph members.
- Network interface to connect to the uplink network
MicroCloud requires one network interface for connecting OVN to the uplink network. This network interface must either be an unused interface that does not have an IP address configured, or a bridge.
MicroCloud configures this interface as an uplink interface that provides external connectivity to the MicroCloud cluster.
You can specify a different interface to be used as the uplink interface for each cluster member. MicroCloud requires that all uplink interfaces are connected to the uplink network, using the gateway and IP address range information that you provide during the MicroCloud initialization process.
Optional network interfaces¶
MicroCloud needs additional network interfaces to implement either of the following optional setups:
Dedicated networks for Ceph: see How to configure Ceph networking
Dedicated underlay network for OVN traffic: see How to configure an OVN underlay network
These interfaces can be physical NICs, or VLAN interfaces on top of one or more physical bonded NICs.
Uplink network¶
To configure external connectivity, MicroCloud requires an uplink network that supports broadcast and multicast. See the LXD documentation on the OVN network.
Cluster member IP addresses¶
The IP addresses of the cluster members must not change after installation, so they must be configured as static addresses.
Software requirements¶
MicroCloud requires snapd version 2.59 or newer.
We recommend an LTS version of Ubuntu 22.04 or newer. Production deployments subscribed to Ubuntu Pro are required to use an LTS version.
If you intend to use ZFS storage, use a non-HWE (Hardware Enabled) variant of Ubuntu 22.04.
Also see LXD’s Requirements and Ceph’s OS Recommendations.
Snaps¶
To run MicroCloud, you must install the following snaps:
See How to install MicroCloud for installation instructions.