[Samba] Oplock break failed on sysvol share

[George]

Hi team!

Samba 4.1.11 on Debian Wheezy here, configured as a DC. I recently started
noticing long startup times for the Windows clients, whenever multiple
clients are started at the same time. For example, at 8:00 AM (when around
30 PCs get started simoultaneously, I get this in smbd.log:

###
[2014/09/16 08:01:21.320944,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{95953CB2-46B9-4F52-A163-87232A8ED688}/GPT.INI --
replying anyway
[2014/09/16 08:01:21.365313,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{FA5D59F2-50FD-4BE4-B21E-9D063676D9E2}/GPT.INI --
replying anyway
[2014/09/16 08:01:51.344249,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{2EB06FF4-4AFF-4A94-8D23-818F8CA9B4FA}/GPT.INI --
replying anyway
[2014/09/16 08:01:51.373489,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{08F3A665-41CB-4DFA-B868-89D1C60D0EBB}/GPT.INI --
replying anyway
[2014/09/16 08:02:21.363013,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{87C94E2B-73DB-4730-86F6-40BE9261049D}/GPT.INI --
replying anyway
[2014/09/16 08:02:21.381695,  0]
../source3/smbd/oplock.c:335(oplock_timeout_handler)
  Oplock break failed for file
mydomain.com/Policies/{950F4DEB-59F3-4617-8EA5-23AF6A3A6413}/GPT.INI --
replying anyway
###

This keeps throwing errors for aprox 8 minutes and then everything turns
back to normal and runs smoothly. I'm not sure why it doesn't always
happen, though.

Any thoughts? I know there are several oplock related features on smb.conf
but not sure about their real world effects.

Thanks a lot.

George