Overview of the Issue

NetScaler High Availability (HA) offers seamless failover capabilities to maintain uninterrupted access to applications, even in the face of hardware failures, maintenance activities, or unexpected outages.Netscaler HA operates on the principle of redundancy, where multiple NetScaler appliances work in tandem to provide a resilient infrastructure. This setup not only enhances the availability of applications but also mitigates the risk of downtime. 

These articles help customers to troubleshoot the most common issues related with HA, such as failover, sync problems, missed heartbeats, etc.

Appendix: Top Knowledge Content

Troubleshooting Common Problems

• CTX282530 - HA Sync Error after Upgrade
• CTX286560 - ADC- HA Sync failure Error: Unable to connect to Primary. Please check the network connectivity from secondary to Primary
• CTX459694 - HA sync issue between primary and secondary node
• CTX217788 - High Availability Failovers Due to Missed HA HeartBeats of NetScaler VPX on VMware ESX Hypervisor
• CTX23979 - "Database streaming channel is broken between HA nodes" error on ADM HA pair
• CTX457792 - Virtual Servers and Service Groups DOWN after secondary ADC upgrade
• CTX477303 - NetScaler HA interface report "No HA heartbeats"
• CTX227906 - HA failover due to insufficient memory allocation
• CTX223257 - Backup and Restore Cluster Netscaler

Tools and Resources

• Citrix ADC Clustering Simplified Into 3 Easy Steps(for clustering of Citrix ADCs which are not on SDX)
• Citrix ADC High Availability Counters 
• How to debug and resolve ADM-HA DB Streaming broken issues

This article provides a list of Knowledge Base resources on how to investigate, troubleshoot, and prevent the most common issues with Netscaler High Availability (HA).