Back to DocsMonitoring your server's resources is essential to understand if the system is running correctly or approaching its limits.
CPU and RAM in real time
top: basic monitor (already installed)
top
Useful keys inside top:
htop: advanced monitor (recommended)
# Installation
apt install htop # Debian/Ubuntu
dnf install htop # CentOS/AlmaLinux
# Launch
htop
htop shows graphical bars for each CPU core and RAM, and is much more readable than top.
- P: sort by CPU
- M: sort by RAM
- k: kill a process (enter the PID)
- q: exit
Current RAM usage
free -h
Example output:
total used free shared buff/cache available
Mem: 3.8G 1.2G 800M 45M 1.8G 2.4G
RAM: 4.0G 0B 4.0G
The available column is the one that matters: it's the RAM actually available for new processes.
Current disk usage
df -h
To see only the main partition:
df -h /
Processes consuming the most resources
Top 10 processes using the most CPU:
ps aux --sort=-%cpu | head -11
Top 10 processes using the most RAM:
ps aux --sort=-%mem | head -11
Real-time network traffic
# Install nethogs to see traffic by process
apt install nethogs
nethogs
# Or iftop to see traffic by connection
apt install iftop
iftop
Disk I/O statistics
# Show disk I/O in real time
iostat -x 1
# To install (if not present)
apt install sysstat
System load (load average)
uptime
Example output:
14:32:01 up 5 days, 3:21, 1 user, load average: 0.12, 0.08, 0.05
The three values are the load average for the last 1, 5 and 15 minutes. A value equal to the number of CPU cores indicates 100% utilization. Higher values indicate that there are processes waiting.
To find out how many cores you have:
nproc
Related articles
Server Reboot
How to properly restart your VPS or VDS, both via SSH and from the control panel
Disk Management
How to check disk space, find large files and free up disk space
Expand Disk After Upgrade
After expanding the VPS disk from the panel, extend the partition and filesystem without losing data.
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