Why is the default size for the FailoverClustering_Diagnostic log 18014398507384832 KB?

Brian Illner 31 Reputation points
2020-11-06T14:26:43.697+00:00

We have two Server 2019 Hyper-V Clusters currently running in our environment. After researching some unexpected C drive freespace loss, we discovered that the FailoverClustering_Diagnostic log size on each host in both clusters was set to 18014398507384832 KB (or 18014 PB).

We certainly didn't manually set these to such an absurd size, so was this the default? Or did something else change it?

Hyper-V
Hyper-V
A Windows technology providing a hypervisor-based virtualization solution enabling customers to consolidate workloads onto a single server.
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Windows Server Clustering
Windows Server Clustering
Windows Server: A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.Clustering: The grouping of multiple servers in a way that allows them to appear to be a single unit to client computers on a network. Clustering is a means of increasing network capacity, providing live backup in case one of the servers fails, and improving data security.
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  1. Xiaowei He 9,871 Reputation points
    2020-11-11T03:13:28.613+00:00

    Hi,

    I tested in my lab and get the same result with you on the Server 2019 cluster (Clean install of Server 2019 OS not upgrade):

    38905-microsoftteams-image-5.png

    In this situation, I would suggest you turn to uservoice to feedback this issue:

    https://windowsserver.uservoice.com/forums/295047-general-feedback

    Thanks for your time!
    Best Regards,
    Anne

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  1. Brian Illner 31 Reputation points
    2020-11-10T13:58:49.683+00:00

    Hi @Xiaowei He - these logs are located in the C:\Windows\System32\winevt location like your example.

    It appears that this is a bug and that the "Set-ClusterSize" command causes this issue.

    After discovering this issue, I had manually reduced each log via Event Viewer to a much smaller size.

    When I ran "Set-ClusterSize -size 2048" as per your instructions, the FailoverClustering/Diagnostic log max size jumped back up to 18014398507384832KB again

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  2. Brian Illner 31 Reputation points
    2020-11-10T14:08:45.853+00:00

    I don't know if this is related or not, but both of these hyper-v clusters were originally 2016 and were recently upgraded to 2019.

    PS C:\Windows\system32> get-cluster | select ClusterFunctionalLevel,ClusterLogLevel,ClusterLogSize

    ClusterFunctionalLevel ClusterLogLevel ClusterLogSize 

                    10               3           2048
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  3. Xiaowei He 9,871 Reputation points
    2020-11-09T07:09:39.967+00:00

    Hi,

    1. I would like to check where is the log file "FailoverClustering_Diagnostic" locate, in C:\Windows\Cluster\Reports or in C:\Windows\System32\winevt or other location?

    2.Please check the log maximum in the following place, open Event viewer, open Applications and Services Logs > Microsoft > Windows > FailoverClustering > Diagnostic, then right-click it and click "Properties", my settings below is by default:

    38245-image.png

    3.Please try to use the following PowerShell command to set the Cluster log size, check if it could help：

    https://learn.microsoft.com/en-us/powershell/module/failoverclusters/set-clusterlog?view=win10-ps

    Thanks for your time!
    Best Regards,
    Anne

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  4. Mark Underhill 1 Reputation point
    2022-05-02T18:45:00.237+00:00

    I find the size of this event log keeps increasing back to this huge size even after I edit the maximum size. It is a real problem as disk space runs out eventually. I also have updated to 2019 and run the Set-ClusterSize command as recommended by MS.
    Has this bug been acknowledged by MS?

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