What is the difference between Prometheus and VictoriaMetrics? How did you configure scrape from multiple clusters?

Prometheus is a popular open-source monitoring and metrics collection system focused on data collection via pull model (scrape). VictoriaMetrics is a high-performance time-series database compatible with Prometheus API, optimized for large volumes of data and long-term storage.

Main differences:

• Performance and scalability: VictoriaMetrics handles large loads and long-term data storage better.
• Compatibility: VictoriaMetrics is fully compatible with Prometheus, supporting the same data format and API.
• Architecture: Prometheus is usually used as a standalone monitoring server, while VictoriaMetrics acts as a backend for storage.

To configure scrape from multiple clusters, one of the following approaches is usually used:

1. Centralized Prometheus with federation: Each cluster has its own Prometheus collecting local metrics, and a central Prometheus collects aggregated data via federation.

2. Pushgateway or remote_write: Metrics from clusters are sent to a centralized storage (e.g., VictoriaMetrics) via remote_write.

3. Scrape from multiple clusters directly: Prometheus configuration specifies endpoints of all clusters if they are accessible over the network.

Example configuration for scraping multiple clusters in Prometheus:

scrape_configs:
  - job_name: 'cluster1'
    static_configs:
      - targets: ['10.0.0.1:9100', '10.0.0.2:9100']
  - job_name: 'cluster2'
    static_configs:
      - targets: ['10.1.0.1:9100', '10.1.0.2:9100']

If clusters are isolated, federation or remote_write is often used for centralized collection.