Enterprise Manager - Cluster Manager
Manage ColdFusion clusters and configure load balancing across instances
Overview
The Cluster Manager in ColdFusion Enterprise Manager provides centralized control over ColdFusion clusters, enabling you to group multiple server instances for load balancing, high availability, and simplified management. Clusters distribute incoming requests across member instances to improve performance, reliability, and scalability.
This page is available only in ColdFusion Enterprise Edition and requires Enterprise Manager to be configured.
Cluster Configuration
Essential settings for creating and configuring ColdFusion clusters.
Cluster Name
PurposeUnique identifier for the cluster
RequirementsMust be unique across all clusters in Enterprise Manager
RecommendationUse descriptive names that indicate purpose (e.g.,
production-web, api-cluster)Best Practice: Use consistent naming conventions across your infrastructure. Include environment and purpose in cluster names (e.g.,
prod-web-cluster, dev-api-cluster).Multicast Port
PurposePort for cluster member communication and session replication
Default45564
RecommendationUse default unless port conflicts exist
FirewallEnsure multicast traffic is allowed between cluster members
Network Requirement: All cluster members must be on the same network segment with multicast enabled, or use sticky sessions without session replication.
Sticky Sessions
PurposeRoute user requests to the same server instance for session consistency
DefaultEnabled
RecommendationEnable for optimal performance unless full session replication is required
ImpactReduces session replication overhead and improves performance
Tradeoffs:
- With Sticky Sessions: Better performance, but users lose session if their instance fails
- Without Sticky Sessions: Full failover capability, but higher overhead from session replication
Adding Cluster Members
Configure server instances to join the cluster.
Instance Selection
PurposeChoose which ColdFusion instances to add to the cluster
RequirementsInstances must be registered with Enterprise Manager and running the same ColdFusion version
RecommendationUse instances with similar hardware specifications for balanced load distribution
Best Practices:
- Add at least 2 instances for high availability
- Use 3+ instances for production clusters to handle member failures
- Ensure all instances have identical application code and configurations
- Test cluster failover before deploying to production
Member Weight
PurposeRelative priority for load distribution across cluster members
Default1 (equal weight for all members)
RecommendationAdjust based on hardware capacity (higher weight for more powerful servers)
ExampleServer with 16 cores gets weight 2, server with 8 cores gets weight 1
Load Distribution: If Server A has weight 2 and Server B has weight 1, Server A receives approximately twice as many requests as Server B.
Load Balancing Configuration
Configure how requests are distributed across cluster members.
Round Robin
- Default
- Yes
- How It Works
- Distributes requests evenly across all cluster members in rotation
- Best For
- Uniform request patterns and similar server specifications
Simple and effective for most use cases with homogeneous servers.
Weighted Round Robin
- Default
- No
- How It Works
- Distributes requests based on configured member weights
- Best For
- Clusters with varying server capacities
Use when cluster members have different hardware specifications.
Least Connections
- Default
- No
- How It Works
- Routes requests to the member with fewest active connections
- Best For
- Variable request duration (mix of quick and long requests)
Optimal for workloads with unpredictable request processing times.
Session Management
Session Replication
PurposeReplicate session data across cluster members for failover
DefaultEnabled (when sticky sessions are disabled)
RecommendationDisable if using sticky sessions to reduce network overhead
ImpactIncreased network traffic and CPU usage, but provides seamless failover
Performance Impact: Session replication can significantly impact performance with large session data or high traffic. Consider storing minimal data in session scope.
Optimization Tips:
- Keep session data small and simple (avoid storing large objects)
- Use external session storage (Redis, database) for critical session data
- Enable sticky sessions to reduce replication frequency
- Monitor network bandwidth usage during peak traffic
Health Monitoring
Health Check Interval
PurposeFrequency of health checks on cluster members
Default30 seconds
Recommendation15-30 seconds for production environments
ImpactFaster detection of failed instances, but increased monitoring overhead
Best Practice: Balance detection speed with monitoring overhead. Too frequent checks waste resources; too infrequent delays failover.
Auto-Remove Failed Members
PurposeAutomatically remove unresponsive instances from the cluster
DefaultEnabled
RecommendationEnable for production to maintain cluster health
ImpactPrevents routing requests to failed instances
Important: Configure alerting to notify administrators when instances are removed from the cluster so issues can be investigated and resolved.
Common Issues & Solutions
Cluster Members Not Communicating
Symptom: Instances appear in cluster but do not share session data or coordinate
Solutions:
- Verify firewall allows multicast traffic on configured port
- Ensure all cluster members are on same network segment
- Check that multicast port is not in use by other applications
- Verify network switches support multicast (IGMP snooping configured correctly)
- Review ColdFusion logs for cluster communication errors
Unbalanced Load Distribution
Symptom: Some cluster members receive significantly more requests than others
Solutions:
- Verify load balancer configuration (check algorithm and member weights)
- Ensure sticky sessions are configured correctly (check cookie/URL parameters)
- Review web server connector configuration for proper worker definitions
- Check that all cluster members are reporting as healthy
- Monitor request processing times (slow instances get fewer requests in least-connections mode)
Session Loss After Instance Failure
Symptom: Users lose sessions when a cluster member fails
Solutions:
- Verify session replication is enabled and functioning
- Check that multicast communication is working between members
- Ensure
this.sessionCluster = truein Application.cfc - Review session scope usage (only serializable data can replicate)
- Consider external session storage (Redis, database) for critical applications
- Test failover scenario in non-production environment