Recently, a large customer of mine running Skype for Business Server 2015 CU5 on Windows Server 2012R2 started noticing Front-End Servers complaining that they lost access to their DFS file share. The occurrences were random in nature and possibly related to a recent Windows Server patching cycle.
It was brought to their attention by the following SCOM alerts:
Alert: [Skype] No write access to the file share.
Source: Conferencing Announcement Service Component [SfBFE02.mycomany.com]
Last modified by: System
Last modified time: 9/6/2017 9:00:23 AM
Alert description: No write access to the file share.
There is a problem accessing file share: \\mycompany.com\skypeforbusinessfileshare\BDCFsData\3-ApplicationServer-1\AppServerFiles\CAS
Cause: No write access to the file share.
Make sure that the permissions are set correctly.
And this one:
Alert: [Skype] Could not extract file share information from local management store.
Source: Conferencing Announcement Service Component [SfBFE02.mycompany.com]
Last modified by: System
Last modified time: 9/6/2017 9:17:42 AM
Alert description: Could not extract file share information from local management store.
Cause: Conferencing Announcement Service might not have been installed correctly.
Make sure that the permissions are set correctly and Conferencing Announcement Service is run in a supported scenario.
Please see the 'Product Knowledge' and the 'Alert Context' tab on Alert Properties view for more information.
The event logs on the server showed the following errors:
Log Name: Lync Server
Source: LS Storage Service
Date: 9/7/2017 9:51:56 AM
Event ID: 32008
Task Category: (4006)
Message=Error: Path \\mycompany.com\skypeforbusinessfileshare\BDCFsData\3-WebServices-1\StorageService failed to be read for flushed data. Error details: System.IO.IOException: Element not found.
Attempting to access the file share from windows explorer would yield the following message:
Given this environment used a Windows Distributed File Share (DFS) for the Skype file share I assumed it was something to do with a DFS client issue.
Restarting the Front End Server would correct the problem, however this is not always practical in the middle of the working day.
After researching this a bit further, I found you could flush the DFS client cache using the following cmd:
PS C:\Windows\system32> .\dfsutil.exe cache referral flush
DfsUtil command completed successfully.
Note: Skype for Business Front End servers typically don’t have the DFS tools so you will need to install them to use this command. The installation of the DFS tools does not require a reboot. You can do this using the following PowerShell cmdlet
Add-WindowsFeature -Name "RSAT-DFS-Mgmt-Con"
After running this and checking Windows Explorer the file share was once again accessible. While this does not address the root cause it will correct the issue and save you from rebooting the server. If this continues to be a problem I’ve advised the client open a PSS ticket to troubleshoot further. Will update this post if the root cause if found.