A while ago, I encountered a Cluster Shared Volume error in my lab. I logged into the Failover Cluster Manager and noticed multiple error status messages in the Cluster Events log. The System Log Event ID 5125 kept showing up every three minutes:

Error Event id 5125 with details: Cluster Shared Volume ‘Volume1’ (‘Cluster Disk 1’) has identified one or more active filter drivers on this device stack that could interfere with CSV operations. I/O access will be redirected to the storage device over the network through another Cluster node. This may result in degraded performance. Please contact the filter driver vendor to verify interoperability with Cluster Shared Volumes.

Active filter drivers found:

AAFsFlt (Continuous Backup)

Navigating to the Storage-Disks folder in Failover Cluster Manager, I noticed that Cluster Disk 1 cluster shared volume showed a “Redirected Access Mode ” status. I resolved the problem in the following steps :

Troubleshooting Step 1:

Highlight the Cluster Disk, in the volumes section, right click the volume and select to ‘Turn off Redirected Mode’ . I got a return message that the ‘Set Operation failed’.

Troubleshooting Step 2:

I checked the iSCSI initiator configuration on each node, navigated to Disk Management to check the status of the disks on each cluster node and everything seemed good.

Troubleshooting Step 3:

I did a quick search online and found the following technet article : http://blogs.technet.com/b/askcore/archive/2010/12/16/troubleshooting-redirected-access-on-a-cluster-shared-volume-csv.aspx .

This pointed me in the right direction . I ran a remote powershell session into the cluster nodes and ran the following command:

PS C:\> Enter-PSSession -ComputerName hyperv02

[hyperv02]: PS C:\Users\admin\Documents> fltmc.exe

npsvctrig                               1        46000         0

According to the event log, the issue was caused by a faulty filter driver “AAFsFlt” that put the Cluster Shared Volume in a continuous backup mode. My backup software is Dell AppAssure 5.4.0 and I couldn’t find a patch for this issue. So I decided to uninstall the agents and reinstall. Moving forward, I changed my backup strategy to protect the virtual machines instead of the CSV. I’m running Hyper-v core on each node, so I used the following PowerShell code to remove and automatically restart the nodes to complete the uninstall :

[hyperv02]: PS C:\Users\admin\Documents> Get-WmiObject -Class win32_product -Filter "Name like '%apprecover%'" | ForEach-Object {$_.uninstall()}

I ran the above code to uninstall the Backup Agent on both nodes. After the restart, the CSV volumes’ status changed state to normal. I hope these steps help point someone in the right direction to resolving the problem.