Reference: Installation requirements

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Before installing MAAS, confirm that your system has adequate resources. These vary by use-case. This page offers a guide based on using Ubuntu Server for test and production setups.

LXD

If you plan to use LXD to create virtual machines with MAAS, you need to use LXD version 5.21 or higher. Older versions will not work correctly with MAAS.

PostgreSQL

From version 3.5, MAAS requires PostgreSQL 14 or higher, as well as a change in the allowed PostgreSQL default user.

Warning: Default configuration of PostgreSQL may not be enough for MAAS 3.5 HA deployments, as MAAS now requires more connections towards your database. For every Region Controller you need to consider at least an additional 20 connections. A safer move would be to have +50 for every Region Controller. You can check your current settings using psql or by getting information from the configuration file. Both methods are demonstrated below.

Getting information using psql

You can check existing connection settings and utilisation using the following SQL query.

SELECT 
  max_conn, 
  used
FROM 
  (SELECT count(*) used FROM pg_stat_activity) t1,
  (SELECT setting::int res_for_super FROM pg_settings WHERE name=$$superuser_reserved_connections$$) t2,
  (SELECT setting::int max_conn FROM pg_settings WHERE name=$$max_connections$$) t3;

max_conn is the maximum number of connections available and used is the number of currently used connections.

Getting information via configuration file

grep 'max_connections' /var/lib/pgsql/{version_number}/data/postgresql.conf

Increasing maximum connections

If you have max_connections set to 100, then you need to increase that number. Please consider referring to these best practices for configuring your PostgreSQL.

Symptoms of an issue

If the configured amount of database connections is not enough, you might see errors like this:

> FATAL: sorry, too many clients already
> FATAL:  remaining connection slots are reserved for non-replication superuser connections
> pq: remaining connection slots are reserved for non-replication superuser connections

That will lead to variety of issues, so please make sure you’ve configured enough connections.

MAAS, NTP, and chrony

Time sync complications can arise between Ubuntu’s default systemd-timesyncd and MAAS chrony. If the NTP servers differ, you’re asking for trouble. Consult the MAAS installation guide for solutions.

Test environment

For a single-host test setup assuming the latest two Ubuntu LTS releases:

Component Memory (MB) CPU (GHz) Disk (GB)
Region controller 512 0.5 5
PostgreSQL 512 0.5 5
Rack controller 512 0.5 5
Ubuntu Server 512 0.5 5

Total? 2 GB RAM, 2 GHz CPU, 20 GB disk.

Production environment

For large-scale, continuous client handling, plan as follows:

Component Memory (MB) CPU (GHz) Disk (GB)
Region controller 2048 2.0 5
PostgreSQL 2048 2.0 20
Rack controller 2048 2.0 20
Ubuntu Server 512 0.5 5

You’ll need about 4.5 GB RAM, 4.5 GHz CPU, and 45 GB disk per host for region controllers, and slightly less for rack controllers.

Additional notes:

  • These specs are MAAS-specific and don’t cover extra nodes.
  • IPMI-based BMC controllers are recommended for power management.

Factors affecting these numbers:

Don’t forget, a local image mirror could significantly increase disk requirements. Also, rack controllers have a 1000-machine cap per subnet. For larger networks, add more controllers.

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