netdata/docs/store/change-metrics-storage.md

Change how long Netdata stores metrics

import { Calculator } from '../../src/components/agent/dbCalc/'

The database engine uses RAM to store recent metrics. When metrics reach a certain age, and based on how much system RAM you allocate toward storing metrics in memory, they are compressed and "spilled" to disk for long-term storage.

The default settings retain about two day's worth of metrics on a system collecting 2,000 metrics every second, but the Netdata Agent is highly configurable if you want your nodes to store days, weeks, or months worth of per-second data.

The Netdata Agent uses two settings in netdata.conf to change the behavior of the database engine:

[global]
    page cache size = 32
    dbengine multihost disk space = 256

page cache size sets the maximum amount of RAM (in MiB) the database engine uses to cache and index recent metrics. dbengine multihost disk space sets the maximum disk space (again, in MiB) the database engine uses to store historical, compressed metrics. When the size of stored metrics exceeds the allocated disk space, the database engine removes the oldest metrics on a rolling basis.

Calculate the system resources (RAM, disk space) needed to store metrics

You can store more or less metrics using the database engine by changing the allocated disk space. Use the calculator below to find an appropriate value for dbengine multihost disk space based on how many metrics your node(s) collect, whether you are streaming metrics to a parent node, and more.

You do not need to edit the page cache size setting to store more metrics using the database engine. However, if you want to store more metrics specifically in memory, you can increase the cache size.

⚠️ This calculator provides an estimate of disk and RAM usage for metrics storage, along with its best recommendation for the dbengine multihost disk space setting. Real-life usage may vary based on the accuracy of the values you enter below, changes in the compression ratio, and the types of metrics stored.

Edit netdata.conf with recommended database engine settings

Now that you have a recommended setting for dbengine multihost disk space, open netdata.conf with edit-config and look for the dbengine multihost disk space setting. Change it to the value recommended above. For example:

[global]
    dbengine multihost disk space = 1024

Save the file and restart the Agent with sudo systemctl restart netdata, or the appropriate method for your system, to change the database engine's size.

What's next?

For more information about the database engine, see our database reference doc.

Storing metrics with the database engine is completely interoperable with exporting to other time-series databases. With exporting, you can use the node's resources to surface metrics when viewing dashboards, while also archiving metrics elsewhere for further analysis, visualization, or correlation with other tools.

If you don't want to always store metrics on the node that collects them or run ephemeral nodes without dedicated storage, you can use streaming. Streaming allows you to centralize your data, run Agents as headless collectors, replicate data, and more.