#Evaluating Resources for Global Cluster

#Overview

Use these resource evaluation practices when planning the global cluster for a Multi-Cluster deployment.

Proper node sizing helps the global cluster manage registered clusters, handle synchronization traffic, and process user API and Web Console requests within the performance expectations of your environment.

#Node Sizing

The global cluster is responsible for:

• Maintaining cluster registration and metadata.
• Handling inbound API requests from the Web Console and CLI.
• Coordinating synchronization and heartbeat messages with connected clusters.
• Managing internal controllers and resource reconciliation loops.

Because the global cluster handles both management operations and data aggregation from all connected clusters, plan resource allocation according to the expected scale and workload intensity.

#Baseline Production Sizing

The production-scale sizing depends primarily on:

• Number of managed clusters
• Frequency of synchronization cycles
• Concurrent API request rate (from users or automation)
• Volume of streaming requests
• Number of plugins installed

The following table provides reference configurations validated through internal performance testing.

#Vertical Scaling Guidelines

When increasing load per node (for example, 2× more clusters or higher user concurrency), follow these adjustments:

#Horizontal Scaling Guidelines

When exceeding 100 managed clusters or encountering persistent API latency above 500 ms:

Add nodes to distribute request handling and controller workloads.

#Resource Validation and Monitoring

After deployment, continuously monitor the following metrics to validate node sizing:

100 * (1 - avg by (instance)(rate(node_cpu_seconds_total{mode="idle"}[5m])))

100 * (1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes))

histogram_quantile(
  0.9,
  sum(rate(apiserver_request_duration_seconds_bucket{verb!="WATCH",resource!="events"}[5m])) by (le)
)

histogram_quantile(
  0.99,
  sum(rate(etcd_disk_backend_commit_duration_seconds_bucket[5m])) by (le)
)

#Summary

When sizing the global cluster:

1. Begin with 3 nodes × 16 cores × 32 GB for moderate-scale deployments (≤50 clusters).
2. Scale vertically for higher request concurrency or heavy Web Console usage.
3. Scale horizontally beyond 100 clusters to maintain API responsiveness.
4. Re-evaluate sizing after every significant increase in managed cluster count or sync frequency.

Use these practices to keep resource planning aligned with the growth of your Multi-Cluster environment.