windows_exporter/docs/runbooks/windowshypervreplicationwarning.md

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WindowsHyperVReplicationWarning

Meaning

Hyper-V Replica reports warning health for the virtual machine vm for 15 minutes. Warning health means that some replication cycles missed their interval, that more than a fifth of the cycles in the last hour failed, or that the replication is waiting for an initial copy or a resynchronization. The alert carries the relationship label and needs the hyperv collector with its replica_vm subcollector. WindowsHyperVReplicationCritical follows when replication stops working.

Impact

The replica lags behind the primary more than planned. The recovery point objective is at risk, and a failover would lose more changes than expected.

Diagnosis

1. Inspect windows_hyperv_replica_vm_health, windows_hyperv_replica_vm_state and windows_hyperv_replica_vm_replication_latency_seconds for the virtual machine, and windows_hyperv_replica_vm_average_replication_size_bytes to see whether the change rate of the virtual machine has grown.

2. On the primary host, read the statistics of the last hour:

   Measure-VMReplication -VMName '<vm>' | Format-List *
   Get-VMReplication -VMName '<vm>' | Format-List State, Health, LastReplicationTime, FrequencySec
   

3. Check the bandwidth between the hosts, the load on the replica storage, and whether the replication interval is too short for the change rate of the virtual machine.

Mitigation

Relieve the bottleneck: more bandwidth, less load on the replica storage, or a longer replication interval through Set-VMReplication -ReplicationFrequencySec. Resume a waiting replication with Resume-VMReplication. Reset the statistics with Reset-VMReplicationStatistics after the fix; the health is computed over the last hour and takes up to an hour to return to normal.