> Source: [sk182829](https://support.checkpoint.com/results/sk/sk182829)

# sk182829 - Split-Brain Condition in ClusterXL and Quantum Maestro Dual-Site After Site Sync Failure and Restoration

| Property | Value |
|----------|-------|
| Solution ID | sk182829 |
| Date Created | 2024-11-25 |
| Last Modified | 2025-10-10 |
| Technical Level | Advanced |
| Products | Security Gateway, Scalable Platforms |
| Versions | R81.20, R81.20 |
| OS | Gaia |

## Symptoms

- * After upgrading one Cluster Member (whether the Cluster works in the Gateway mode or VSX mode) to the R81.20 Jumbo Hotfix Accumulator Take 14 or higher, the output of the "`cphaprob state`" command on the not upgraded Cluster Member shows that its cluster state is "`Ready`" and does not change to "`Active`".
* In Maestro, the environment becomes unavailable until you execute manual failover commands (chassis_admin down/up).
* Upon restoration, the previously standby site shows at least one Security Group Member (SGM) in the READY state, not STANDBY as expected.
* The issue did not occur in the previous version (R81.10).

## Cause

In R81.20, the Cluster Control Protocol (CCP) version changed as part of the Jumbo Hotfix Accumulator (JHF) from Take 14 onwards. The Multi-Version Cluster (MVC) feature is required for proper state synchronization between sites in this version.  

When the synchronization link failed, both sites transitioned to ACTIVE and sent CCP Security Group Member (SGM) messages with both old and new CCP versions. Upon restoration, a race condition could occur: if the SGM message with the old version arrived before the CCP message with the new version, it would block the state change. This resulted in a persistent split-brain (ACTIVE/ACTIVE) condition until manual intervention. This behavior is specific to R81.20 and later, where enabling MVC is mandatory for ClusterXL.

## Solution

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