H Usage hints and caveats - moudsen/mailGraph GitHub Wiki
Zabbix caching
Please consider using the PERIOD/PERIODS settings wisely as Zabbix will place requested values into it's Cache, likely resulting in "Zabbix value cache working in low memory mode" issues!
Increment the ValueCacheSize
setting in your 'zabbix_server.conf` is this happens (suggest to double the value until the issue resolves as there is no way to predict the exact value of this setting).
Disk filling with images
Safely consider the amount of time images (and logs) may grow rapidly over time on a busy production server. Ensure proper retention of the associated directories to prevent unexpected flooding.
Refer to "A Cleaning up LOG and IMAGES directory" for detailed instructions.