Munin stores its monitoring data in RRD (Round Robin Database) files, typically located in /var/lib/munin/ or /var/cache/munin/www/. Each host has its own directory containing .rrd files for various metrics.

To completely reset graphs for a specific host (e.g., 'webserver01'):

# Navigate to Munin's data directory
cd /var/lib/munin/

# Find all RRD files for the host
find . -name "webserver01*" -type f

# Remove all RRD files for the host
find . -name "webserver01*" -type f -exec rm -f {} \;

# Optional: Clean HTML output if stored separately
cd /var/cache/munin/www/
rm -rf webserver01/

For a more controlled approach without deleting files:

# Use munin-graph to regenerate graphs
munin-graph --host webserver01 --service load --force-graph
munin-graph --host webserver01 --service memory --force-graph

Create a bash script to handle multiple hosts:

#!/bin/bash
HOST="webserver01"
MUNIN_DATA="/var/lib/munin"
MUNIN_CACHE="/var/cache/munin/www"

# Remove RRD files
find "$MUNIN_DATA" -name "${HOST}*" -type f -delete

# Clear HTML cache
rm -rf "${MUNIN_CACHE}/${HOST}"

# Restart munin-node for changes to take effect
systemctl restart munin-node

Before resetting:

• Backup existing data: tar -czvf munin_backup.tar.gz /var/lib/munin/
• Verify disk space for new RRD files
• Consider time periods when monitoring gaps are acceptable

Sometimes, you may need to reset Munin graphs for a specific host due to corrupted data, configuration changes, or simply to start fresh. Munin stores its RRD (Round Robin Database) files in /var/lib/munin/ by default, and these files hold the historical graph data.

First, identify the RRD files associated with the host you want to reset. Navigate to the Munin data directory:

cd /var/lib/munin/

Then, locate the host-specific directory. For example, if your host is named webserver1:

ls webserver1/

To reset the graphs, you need to remove the RRD files for that host. Be cautious—this action is irreversible. Run:

rm /var/lib/munin/webserver1/*.rrd

This command deletes all .rrd files for webserver1. If you want to reset only specific graphs, specify the filenames instead of using *.rrd.

After deleting the RRD files, restart Munin to regenerate the graphs:

systemctl restart munin-node

Or, if you're using an older system:

service munin-node restart

Check the Munin web interface after a few minutes. The graphs for the specified host should now be empty or start fresh. If they don’t regenerate, ensure Munin has write permissions in /var/lib/munin/.

If you frequently reset graphs, consider writing a script. Here’s a Bash example:

#!/bin/bash
HOST="webserver1"
rm /var/lib/munin/$HOST/*.rrd
systemctl restart munin-node
echo "Graphs for $HOST have been reset."

Save it as reset_munin.sh, make it executable, and run it whenever needed.

• Backup RRD files before deletion if the data is critical.
• Ensure Munin has proper permissions to recreate the files.
• Graphs may take a few minutes to reappear in the web interface.