Windows 2012 Server Backup failure with SMB >= 2.1 (FSCTL_LMR_REQUEST_RESILIENCY)

[Jones]

Hi List,

The client OS is Windows Server 2012,
and Windows Server Backup is installed from Server Manager.
The short "WSB" stands for Windows Server Backup in this article.

Trying to perform a single backup to remote shared folder,
which is a location specified on a Samba3/4 server,
or a Widnows 7 PC as comparison.

If WSB is success.
data transferred size is total around 14GB.

If WSB is failure,
log-level-10 message is saved as samba-4.0.5_windows_server_backup_log.smbd,
DL:
https://drive.google.com/file/d/0B3gmHkfiqqWrdDFXVWZBZjhianc/edit?usp=sharing
and wireshark pcap file as samba-4.0.5_windows_server_backup.pcap.
DL:
https://drive.google.com/file/d/0B3gmHkfiqqWrUGRWMTkyTU5JNjQ/edit?usp=sharing

Here are detailed test results:

(A) Server: Samba-3.6.18
===========================
While max protocol =
(A.1) NT1,  WSB is success.
(A.2) SMB2, WSB is success.

(B) Server: Samba-4.0.5
===========================
While max protocol =
(B.1) NT1, WSB is success.
(B.2) SMB2_02, WSB is success.
(B.3) SMB2_10, WSB is failure.
(B.4) SMB3_00, WSB is failure.

(C) Server: Windows 7 Home Premium 64bit
===========================
The negotiated protocol is SMB 2.1 (thru wireshark dialect: 0x210),
and WSB is always success.

(D) FSCTL_LMR_REQUEST_RESILIENCY is involved with SMB >= 2.1
===========================
During WSB is launched,
while Windows Server 2012 and Samba are negotiated with SMB >= 2.1,
the client would issue an additional ioctl request,
with CtlCode = FSCTL_LMR_REQUEST_RESILIENCY.
Samba would fail this request with STATUS_INVALID_DEVICE_REQUEST,
but Windows 7 could handle it well with STATUS_SUCCESS response.

(E) Questions
===========================
In short summary,
While Windows Server 2012 and Samba are negotiated with SMB >= 2.1,
WSB is always failure.
(E.1)
Is FSCTL_LMR_REQUEST_RESILIENCY the failure cause?
(E.2)
Is there a tricky method or magic flag to avoid client issue this fsctl,
or instead,
just made SMB <= 2.0 happened between client and server to avoid this fsctl?
(E.3)
Is this fsctl is kindly put into consideration @ Samba.Org,
or is it already in progress or developing roadmap?
Any suggestion is appreciated,
thanks.

(F) Bugzilla 9938, 10055
===========================
Found similar symptom in following links,
WSB would create a .vhdx file like #9938.
https://bugzilla.samba.org/show_bug.cgi?id=9938
https://bugzilla.samba.org/show_bug.cgi?id=10055

(G) Mailing list
===========================
It is likely FSCTL_LMR_REQUEST_RESILIENCY is not implemented yet.
https://lists.samba.org/archive/samba-technical/2013-September/095190.html

(H) Wiki Samba3/SMB2
===========================
TODO: resilient file handles, persistent file handles
https://wiki.samba.org/index.php/Samba3/SMB2

(I) Microsoft MSDN, Handling a Resiliency Request
===========================
Said: This section applies only to servers that implement the SMB 2.1 or
the SMB 3.x dialect family.
http://msdn.microsoft.com/en-us/library/ee380168.aspx


Regards,
Jones