Introduction
In enterprise IT, real challenges begin when theory ends.
I recently encountered a critical incident in a VMware production environment where over 70 virtual machines were at risk due to simultaneous failures — including a host outage, vSAN degradation, and HA misconfigurations.
In this blog post, I walk through the real-world steps I took to recover the environment, restore stability, and implement permanent improvements that strengthened the infrastructure and reduced risk for the future.
The Situation
- 3-node VMware cluster running vSAN
- One physical host completely failed
- vSAN disk group was in a Degraded state
- HA didn’t function as expected
- vCenter became unstable and intermittently unreachable
This happened during business hours, with critical banking services live.
Root Cause Analysis
After deep inspection, I identified several key issues:
- HA isolation response was misconfigured
- No proactive monitoring in place (no vROps, no Skyline)
- One host had unsupported firmware not aligned with VMware HCL
- Flat Layer 2 network — no separation between management, vMotion, and vSAN traffic
Actions Taken
Within the first hour, I executed an emergency recovery plan:
Accessed ESXi hosts via DCUI and restarted management agents
Verified cluster quorum and rebalanced vSAN objects using RVC
Updated HA settings to tolerate a single host failure
Fixed isolation address (pointed to the correct gateway IP)
Upgraded firmware and validated against VMware HCL
Created separate VLANs for vSAN, vMotion, and Management traffic
Deployed vRealize Operations Manager (vROps) for health visibility
Designed and tested a full DR plan using VMware SRM
Lessons Learned
Key takeaways from this incident:
- HA is only effective if correctly configured
- vSAN demands strict hardware and firmware compliance
- Flat networks are a silent risk — always segment your traffic
- Tools like vROps and Skyline are essential, not optional
- DR isn’t luxury — it’s a survival mechanism
Conclusion
This incident wasn’t just a recovery challenge — it was a wake-up call on the importance of resilient design, proactive monitoring, and configuration accuracy.
By sharing this real-world experience, I hope to help other VMware professionals build stronger, smarter infrastructure — and avoid costly disruptions before they happen.
Visit my platform for more hands-on insights – ITBinary.com
Share Your Experience
Have you faced a similar situation in your VMware environment?
Let’s connect — I’d love to hear how you approached it, and what tools or techniques worked best for you.
Drop a comment or reach out to me at itbinary.com/contact
About the Author
Mohamed Omar is an Infrastructure Architect and VMware Consultant with over 17 years of experience in virtualization, storage, and enterprise IT design. He specializes in building resilient infrastructure solutions using VMware, vSAN, VxRail, and VCF .
