Installation requirements
Confirm that your system has adequate resources for your use-case, prior to installation. Proof-of-concept and production setups are available.
LXD
LXD versions older than 5.21 will not work correctly with MAAS.
PostgreSQL
From version 3.5, MAAS requires PostgreSQL 14 and a different PostgreSQL default user.
Warning: PostgreSQL defaults may not support HA deployments. Consider using 20-50 extra connections per additional region controller. Check settings using
psqlor by inspecting the configuration file.
Getting information using psql
You can count PostgreSQL connections with this 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 number of available connections; used is the number of active connections.
Getting information via configuration file
grep 'max_connections' /var/lib/pgsql/{version_number}/data/postgresql.conf
Increasing maximum connections
If max_connections is 100, you need to increase that number. Refer to these best practices for details.
Symptoms of an issue
Too few database connections tend do produce errors:
> 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
MAAS, NTP, and chrony
Conflicts can arise between Ubuntu’s default systemd-timesyncd and MAAS chrony. Consult the MAAS installation guide for solutions.
Test environment
Requirements for a single-host test setup include the latest two Ubuntu LTS releases and the following component settings:
| 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 |
Plan for 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:
- Client activity
- Service distribution
- Use of high availability/load balancing.
- Number and type of stored images
- A local image mirror will increase disk requirements.
- Rack controllers have a 1000-machine cap per subnet