You may find that the following event fills up Windows Fabric event logs in Microsoft Skype for Business Server 2015 Director pools:
Log Name: Microsoft-Windows-WindowsFabric/Admin
Event ID: 16385
Task Category: Reliability
User: NETWORK SERVICE
Description: FM resolving failed with FABRIC_E_PARTITION_NOT_FOUND Event Xml
This issue occurs because the Windows Fabric cluster isn't set up properly in Skype for Business Server 2015 Director pools that have more than two servers.