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Michael
Michael

Posted on • Originally published at gbase8.cn

Monitoring FoundationDB in GCDW: A Deep Dive into the status Command

#gbase #database #数据库 #monitoring

GCDW (GBase Cloud Data Warehouse) relies on FoundationDB (FDB) for metadata storage. The fdbcli tool's status command provides a comprehensive snapshot of cluster health, redundancy, load, and resource consumption. This guide explains every key section of the status and status details output for your gbase database infrastructure.

At a Glance: What to Check First

Run status inside fdb> and focus on these vital signs:

  • Redundancy mode – single/double/triple; defines your replica count.
  • Fault Tolerance – maximum nodes that can fail without data loss. 0 means any single node failure loses data.
  • Replication health – must be Healthy.
  • Memory availability – per‑process available RAM; a warning appears below 4 GB.
  • Conflict rate – high values indicate transaction contention.

Key Output Sections

Section Metric Meaning
Configuration Redundancy mode double = 2 replicas; triple = 3 replicas
Storage engine ssd-2 (large datasets) or memory-2 (small, fast)
Coordinators Odd number recommended (e.g., 3)
Cluster FoundationDB processes Total FDB server processes; one per CPU core, ≥4 GB RAM each
Fault Tolerance Number of machines that can fail; 0 = no redundancy
Data Replication health Must be Healthy
Moving data Non‑zero during scaling or recovery
Disk space used Total disk consumed by the cluster
Workload Read / Write rate Current throughput in Hz
Transactions started / committed Transactional throughput
Conflict rate Rate of transaction conflicts

Switching the Storage Engine

You can change the storage engine online without downtime:

fdb> configure ssd         # switch to SSD engine
fdb> configure memory-3    # switch to memory engine
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  • SSD engine: Persists data on disk. Best for large datasets. Space reclamation after deletes is delayed.
  • Memory engine: Keeps data in memory, logs to disk. Best for small, fast workloads.

Per‑Process Details with status details

status details exposes resource usage for every FDB server process:

Process performance details:
  10.0.2.81:4500 (  4% cpu;  5% machine; 0.000 Gbps;  1% disk IO; 0.5 GB / 2.7 GB RAM )
  10.0.2.82:4500 (  6% cpu;  2% machine; 0.000 Gbps;  1% disk IO; 0.4 GB / 2.8 GB RAM )
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Each line shows:

  • cpu – single‑core CPU usage of the process.
  • machine – overall CPU utilisation of the host.
  • Gbps – combined network throughput.
  • disk IO – disk busy percentage.
  • RAM – physical memory used by the process / total available per process on that host.

Coordination server reachability is also listed, helping you quickly spot network partitions or down nodes.

Operational Best Practices

  • Keep Fault Tolerance ≥ 1 in production. Prefer double redundancy for safety.
  • Never ignore memory warnings – insufficient RAM leads to OOM kills and performance collapse.
  • Monitor Conflict rate routinely; a persistent spike usually indicates a hot key or poor data model design.
  • During scaling or node replacements, track Moving data to know when rebalancing completes.

Mastering the status command gives you full visibility into the FoundationDB layer of your GCDW gbase database, keeping the metadata backbone healthy and performant.

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