Monitoring the right indicators lets you detect problems before they impact your users. Here are the essential server metrics and how to configure them.
The processor is often the first bottleneck. Excessively high CPU usage slows down all operations.
Normal
< 70%
Warning
70-85%
Critical
> 85%
Also monitor: Load average (1, 5, 15 min), I/O wait, steal time (VM)
Running out of RAM forces the system to use swap (disk), which severely degrades performance.
Normal
< 80%
Warning
80-90%
Critical
> 90% or active swap
Also monitor: Swap usage, OOM killer events, cache/buffers
A full disk can completely lock up a server. Databases and logs are the usual culprits.
Normal
< 70%
Warning
70-85%
Critical
> 85%
Also monitor: Inodes, I/O latency, SMART status (physical drives)
Bandwidth and network latency directly impact the end-user experience.
The most important metric: is your server responding to requests?
Checks to configure:
Verify that your critical services are running and responding correctly.
Web Server
Apache/Nginx: processes, workers, connections
Database
MySQL/PostgreSQL: connections, queries/s, slow queries
PHP-FPM
Active workers, queue, processing time
Cache
Redis/Memcached: hit ratio, memory usage
A backup that has not been verified does not exist. Monitor your backups.
Detect intrusion attempts and abnormal behaviour.
Too many alerts kill alerting. If your team receives 100 notifications a day, they will stop paying attention. Set realistic thresholds and group similar alerts together.
A 3-second CPU spike is not a problem. Configure alerts that only trigger when a threshold is exceeded for X minutes.
Distinguish critical alerts (SMS/phone call) from informational alerts (email). Web server down = immediate call. Disk at 75% = email for action within 24 hours.
Organisation, real costs, and French legal framework
Our plans start from EUR 70/month (business hours) or EUR 150/month (24x7) and include monitoring of all these KPIs, with intelligent alerting and incident response. Need managed Proxmox supervision? We manage your clusters too.