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Important Cluster Health Parameters

Proactive monitoring is essential for maintaining the stability, performance, and reliability of your MooseFS cluster. By observing key components and system metrics, you can detect potential issues early, prevent downtime, and ensure data integrity. This section outlines the most important areas to monitor and provides guidance on tools and methods for doing so effectively.

1. Chunks Matrix Health​

The chunks matrix provides insight into the status of your data across the cluster. Pay special attention to:

  • Missing Chunks – Indicates data loss; should always be addressed immediately.
  • Endangered Chunks – Chunks at risk due to lack of replication.
  • Undergoal Chunks – Chunks not meeting the desired replication goal.

A sudden increase in any of these categories may point to issues such as Chunkserver disconnections or disk failures. A consistently high number of undergoal chunks may also signal redundancy or performance problems.

2. Master Server Metrics​

As the central brain of the cluster, the Master Server is responsible for managing metadata and coordinating system activity. Key metrics to monitor include:

  • CPU Utilization – High usage (close to 100%) may indicate the server is struggling to handle metadata operations.
  • RAM Usage – Metadata is stored in memory. Monitor both total system RAM and memory used specifically by the mfsmaster process. Insufficient RAM can severely impact performance or lead to crashes.
  • Network Latency and Packet Loss – The Master Server must communicate reliably with all components. Watch for delays or dropped packets on its network interfaces.
  • Metadata Operations Rate – Measure the rate of operations like lookup, mknode, and unlink to assess system load.
  • Master Server State (MooseFS Pro) – Monitor the role and status of Leader and Follower Master Servers to ensure proper high-availability (HA) behavior.
  • Disk I/O – While not handling file data, the Master Server writes metadata and changelogs to disk. Monitor latency and throughput for the relevant storage devices.

3. Chunkserver Monitoring​

Chunkservers store the actual file data in the form of chunks. Their performance and health directly affect system reliability and access speed.

  • CPU Utilization – High CPU load may result from client requests or internal operations like replication and balancing.
  • RAM Usage – Monitor the memory used by the mfschunkserver process. Limited RAM can lead to increased disk I/O and slower performance.
  • Disk Space Usage – Ensure each Chunkserver has sufficient available space. Running out of space prevents new data from being stored and may trigger system alerts.
  • Disk I/O (Read/Write Latency and Throughput) – Slow disks impact performance. Identify overloaded or failing drives.
  • Chunkserver Registration – Verify that all expected Chunkservers are connected and visible to the Master Server.
  • Disk Health – Use tools like smartctl (SMART) to detect early signs of disk failure.

4. Network Monitoring​

MooseFS relies on reliable and low-latency network communication between its components. Monitor:

  • Latency – Watch for high latency between any two roles (Client ↔ Master, Client ↔ Chunkserver, Master ↔ Chunkserver, Metalogger/Follower ↔ Master).
  • Throughput – Ensure sufficient bandwidth is available for data transfers, especially between Chunkservers and Clients.
  • Packet Loss and Errors – Frequent errors or dropped packets can cause performance degradation or data unavailability.
  • Network Interface Saturation – Check if any interfaces are consistently maxed out, which could bottleneck performance.

5. Client-Side Monitoring​

Though Clients do not store data, their interaction with the MooseFS cluster is vital:

  • Mount Status – Verify that all Clients are properly mounted to the MooseFS volume.
  • Connectivity – Ensure Clients can reach both the Master Server and the necessary Chunkservers.
  • Client-Side Performance – Monitor read/write speeds and responsiveness. Performance issues may indicate problems elsewhere in the cluster.

6. Monitoring Tools and Methods​

A combination of MooseFS-native tools and standard system monitoring utilities is recommended:

  • MooseFS CGI Monitor – Web-based dashboard showing status of Master, Chunkservers, disk usage, and more.
  • Client-side Stats via mfsmount – Run: 
    cat /mnt/mfs_mount_point/.params
    to display client statistics.
  • MooseFS Prometheus Exporter – Exposes detailed cluster metrics suitable for dashboards and alerting. Ideal for real-time monitoring and trend analysis.
  • Standard Linux Tools – Use tools like top, htop, vmstat, iostat, netstat, or sar for resource-level insights.
  • Dedicated Monitoring Solutions – Tools like Grafana, Zabbix, or Nagios can be integrated with MooseFS to visualize data and configure alerts.

Final Recommendations​

Monitoring is not just about detecting failures - it's about gaining insight into system behavior and anticipating problems before they affect operations. Establish baseline performance metrics early, and use them to detect anomalies or trends that indicate degradation.

By closely monitoring these key areas, you'll improve uptime, maintain data integrity, and ensure your MooseFS cluster performs at its best.