When choosing between Zabbix, Nagios, and Munin for monitoring a small server fleet (under 10 nodes), several technical considerations come into play. Having implemented all three solutions in production environments, I'll share practical insights specifically for small-scale deployments.

The main architectural considerations for Zabbix in small environments:

• Server Requirements: While Zabbix can run on a single server, its MySQL/MariaDB backend grows significantly with retention periods. For 10 nodes with 30-day retention, a 2vCPU/4GB RAM VM suffices.
• Agent Footprint: The Zabbix agent (zabbix_agentd) typically uses 12-25MB RAM per host - lighter than Nagios' NRPE but heavier than Munin's Perl collectors.

# Sample minimal zabbix_agentd.conf for Linux:
Server=192.168.1.100
ServerActive=192.168.1.100
Hostname=web01
EnableRemoteCommands=0
LogFileSize=1
Timeout=3

You can absolutely run Zabbix on an existing lightly-loaded server. Here's a deployment pattern I've used successfully:

# LXC container on Proxmox (2vCPU, 2GB RAM allocation)
apt install zabbix-server-mysql zabbix-frontend-php zabbix-apache-conf zabbix-sql-scripts
mysql -e "CREATE DATABASE zabbix CHARACTER SET utf8 COLLATE utf8_bin"
zcat /usr/share/doc/zabbix-sql-scripts/mysql/create.sql.gz | mysql -uzabbix -p zabbix

Unlike the Nagios/Munin combo, Zabbix provides unified alerting with these advantages:

• Built-in escalation paths (first notify Slack, then SMS if unacknowledged)
• Trigger dependencies (don't alert about MySQL if the host is down)
• Maintenance windows (suppress alerts during patching)

# Example trigger for disk space with hysteresis:
{
  "description": "Disk space on / is less than 5%",
  "expression": "{web01:vfs.fs.size[/,pfree].last()} < 5 and {web01:vfs.fs.size[/,pfree].min(10m)} < 5",
  "recovery_expression": "{web01:vfs.fs.size[/,pfree].min(10m)} > 10"
}

Zabbix's housekeeper process can be tuned for small deployments:

# In zabbix_server.conf:
HistoryStorageURL=mysql://zabbix:password@localhost/zabbix
HistoryStorageDateIndex=1
HousekeepingFrequency=24
MaxHousekeeperDelete=10000

This configuration reduces I/O overhead while maintaining 30 days of metrics for 10 nodes (approximately 15GB storage).

For those considering Nagios/Munin, here's a modernized approach:

# Monitoring stack using Prometheus + Alertmanager + Grafana
# docker-compose.yml snippet:
services:
  prometheus:
    image: prom/prometheus
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
  alertmanager:
    image: prom/alertmanager
  grafana:
    image: grafana/grafana

The choice ultimately depends on your specific monitoring philosophy and existing infrastructure.

When monitoring fewer than 10 servers, the architectural considerations change significantly compared to enterprise deployments. Zabbix's agent-based monitoring typically consumes 3-5% CPU and 50-100MB RAM per monitored host - negligible for modern servers but worth noting for constrained environments.

# Sample Zabbix agent resource usage (CentOS)
$ ps aux | grep zabbix_agentd
zabbix    1234  0.3  1.2 112436 54832 ?        S    Aug01  12:34 /usr/sbin/zabbix_agentd

The Zabbix server component requires more resources - a basic installation needs at least 1GB RAM and 1 CPU core. For your light-load server, this is feasible if:

• Current utilization is below 40% CPU
• You have 2GB+ free RAM
• Disk I/O isn't saturated

Here's a minimal Zabbix server install on Ubuntu alongside other services:

# Install Zabbix server with MySQL
sudo apt install zabbix-server-mysql zabbix-frontend-php zabbix-apache-conf zabbix-agent

# Configure DB (run on your existing MySQL instance)
CREATE DATABASE zabbix CHARACTER SET utf8 COLLATE utf8_bin;
CREATE USER 'zabbix'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON zabbix.* TO 'zabbix'@'localhost';

For better isolation on a shared server:

# Docker-compose snippet for Zabbix
version: '3'
services:
  zabbix-server:
    image: zabbix/zabbix-server-mysql
    ports:
      - "10051:10051"
    environment:
      DB_SERVER_HOST: mysql-host
      MYSQL_USER: zabbix
      MYSQL_PASSWORD: password

For truly lightweight monitoring consider Zabbix's agentless options:

# Simple ICMP ping check
UserParameter=ping.check[*],ping -c 3 $1 | grep 'packet loss' | awk '{print $6}'

The choice ultimately depends on your growth plans. Zabbix scales better if you anticipate adding more servers or monitoring types later.