Time Series Storage

Horizon stores performance data in a time series storage, JRobin by default. For different scenarios you may want to use a different time series storage. The following implementations are installed by default:

Table 1. Supported time series databases
JRobin	JRobin is a clone of RRDTool written in Java. It does not fully cover the latest feature set of RRDTool and is the default when you install Horizon. Data is stored on the local file system of theHorizon node. Depending on I/O capabilities it works well for small- to medium-size installations.
RRDTool	RRDTool is actively maintained and the de-facto standard for time series data. Data is stored on the local file system of the Horizon node. Depending on I/O capabilities it works well for small- to medium-size installations.
Newts	Newts is a database schema for Cassandra. The time series is stored on a dedicated Cassandra cluster, which gives growth flexibility and lets time series data persist in a large scale.

You can use time series storage integrations with plugins based on our OpenNMS Integration API (OIA). Several plugins are available as a replacement for the ones shipped with OpenNMS Horizon (see time series integration layer).

This section describes how to configure Horizon to use RRDTool and Newts.

The way data is stored in different time series databases makes it extremely hard to migrate from one technology to another. You cannot prevent data loss when you switch from one to another.