Extension:Prometheus rev 01

Prometheus is a metrics database that works in the background as part of the storage server's monitoring feature. Once installed, it continuously collects system, storage, and hardware sensor data and makes that data available to the dashboards provided by the Grafana extension.

Note: Prometheus is delivered as an optional Small Update (the xc-prometheus module). This article describes revision 01. If your system was updated to a newer revision, refer to the matching Extension:Prometheus_rev_NN article.

How it works

Prometheus is a companion extension for the monitoring dashboards feature — it has no page of its own in the GUI. It works together with two other extensions:

• The Metrics exporters extension, which gathers system, storage, and hardware sensor data on the storage server.
• The Grafana extension, which reads the collected data from Prometheus and displays it as dashboards in your browser.

All three extensions — Metrics exporters, Prometheus, and Grafana — must be installed for the dashboards to display data.

Once installed, Prometheus runs automatically in the background. There is nothing to configure, and no separate login or user interface — all interaction with the collected metrics happens through the Grafana dashboards. Measurements are collected every 15 seconds, which determines how fine-grained the data shown in the dashboards is.

To view the metrics that Prometheus collects, open the dashboards provided by the Grafana extension.

Network access

Prometheus is available only on the storage server itself. It provides its web interface and query API on port 9090, bound to the local host (127.0.0.1), and is not reachable from the network. Only local services running on the same storage server — such as the Grafana extension — can access it, so the collected monitoring data is never exposed outside the appliance.

Known issues and limitations

• All companion extensions must be installed. Prometheus has no data to collect without the Metrics exporters extension, and no dashboards can display its data without the Grafana extension. If any of the three extensions is missing, the dashboards will show No data for all panels.

Storage and data retention

The metrics database automatically keeps roughly the last 15 days of measurements; older data is discarded automatically, so there is nothing to clean up.

It uses a dedicated storage area of about 1 GB. Under normal operation, 15 days of metrics use only a fraction of that space, so the database does not fill up in typical use.

If the storage area ever fills — for example after an unusually high volume of metrics — the database temporarily pauses recording new measurements until space is automatically reclaimed as the oldest data ages out. No user action is required; it recovers on its own. The only visible effect is a gap in the dashboards for the affected period, and existing data and other services are unaffected.

Changelog

rev 01

• Initial release of the Prometheus metrics-database extension.

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To view or troubleshoot the collected metrics, see the Grafana extension article or contact Open-E support.