In addition to the DFSR.exe process maxing out CPU on the file server, the following error was being generated on a regular basis:
Log Name: Application
Date: 7/07/2016 2:33:18 PM
Event ID: 623
Task Category: Transaction Manager
DFSRs (1696) \\.\E:\System Volume Information\DFSR\database_5AAC_EEEA_ACEE_C01D\dfsr.db: The version store for this instance (0) has reached its maximum size of 127Mb. It is likely that a long-running transaction is preventing cleanup of the version store and causing it to build up in size. Updates will be rejected until the long-running transaction has been completely committed or rolled back.
Possible long-running transaction:
Session-context ThreadId: 0x00000000000012BC
Session-trace: 32997@2:32:18 PM
If you installed update rollup 3156418 on Windows Server 2012 R2, the DFSRS.exe process may consume a high percentage CPU processing power (up to 100 percent). This may cause the DFSR service to become unresponsive to the point at which the service cannot be stopped. You must hard-boot affected computers to restart them.
To work around this problem, uninstall update rollup 3156418.
Microsoft is aware of this problem and is working on a solution.
Make sure you do not install KB3156418 on any DFSR nodes until this issue has been fixed by Microsoft.