The atop performance monitoring tool by default stores daily log files in /var/log/atop/ with a 28-day retention period. This can quickly accumulate to several gigabytes of disk space (3.5GB in your case). The binary log files (typically named atop_YYYYMMDD) contain system performance metrics collected at regular intervals.

There are two primary ways to control atop's logging behavior:

# Method 1: Configure log rotation in /etc/atop/atop.daily
# This controls the cron job that rotates atop logs
LOGGENERATIONS=7  # Keep logs for 7 days instead of 28
LOGPATH="/var/log/atop"  # Verify log directory
INTERVAL=600      # Set collection interval in seconds (default 600)

# Method 2: Edit /etc/default/atop (Debian/Ubuntu) or /etc/sysconfig/atop (RHEL)
# Set these parameters:
INTERVAL=300      # 5-minute collection interval
LOGGEN=14         # Keep logs for 14 days

To immediately clean up old log files while waiting for configuration changes to take effect:

# Remove logs older than 7 days
find /var/log/atop -type f -name 'atop_*' -mtime +7 -exec rm {} \;

# Alternative: Keep only the most recent N files
ls -t /var/log/atop/atop_* | tail -n +15 | xargs rm

For a permanent solution, modify the atop configuration file (location varies by distro):

# On Debian/Ubuntu systems:
sudo nano /etc/default/atop
# Add or modify these lines:
INTERVAL=300
LOGGEN=7

# On RHEL/CentOS systems:
sudo nano /etc/sysconfig/atop
# Add or modify:
OPTS="-a -w /var/log/atop/atop_$(date +%Y%m%d) 300 7"

After making changes, restart the atop service:

sudo systemctl restart atop
# Or if running as cron job:
sudo /etc/init.d/atop restart

Check the new log rotation behavior after 24 hours by verifying the number of log files in /var/log/atop/.

By default, atop follows a strict daily logging pattern where it:

• Creates new log files at midnight (named atop_YYYYMMDD)
• Compresses files older than 28 days
• Stores everything in /var/log/atop/

The primary configuration file controls log retention. Edit with root privileges:

sudo nano /etc/default/atop

Key parameters to modify:

# Reduce retention from 28 days to 7 days
LOGGENERATIONS=7

# Decrease log interval from default 600s (10 minutes)
INTERVAL=1800  # 30 minutes

# Alternative: Disable daily logging completely
LOGOPTS="-R"

For more granular control, create a logrotate configuration:

sudo nano /etc/logrotate.d/atop

Add these rotation rules:

/var/log/atop/atop_* {
    daily
    missingok
    rotate 7
    compress
    delaycompress
    notifempty
    size 100M
}

To immediately reclaim space:

# Remove logs older than 7 days
find /var/log/atop -type f -mtime +7 -exec rm {} \;

# Alternative: Keep only last 10 files
ls -t /var/log/atop/atop_* | tail -n +11 | xargs rm -f

After modifying configurations:

# Restart atop service
sudo systemctl restart atop

# Check active configuration
atop -r /var/log/atop/atop_$(date +%Y%m%d) -v | head -n 20