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

[Andrew Bartlett]

On Fri, 2013-11-15 at 17:17 +0800, Jones wrote:
> 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.

> (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?

Yes.

> (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?

The only known workaround is:

max protocol = SMB2_02

In particular, changing error codes is not a workaround.  We have tried
this, and confirmed both by testing and directly with Microsoft's
engineers that it would be ineffective. 

> (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.

We are aware of the issue.  

> (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

The correct bug is 
https://bugzilla.samba.org/show_bug.cgi?id=10159

We are working with Microsoft to see if they can address the issue on
their side.  We also know it is important to implement the feature, but
I'm told it's non-trivial. 

I hope this gives you the background you need.  I'm sorry we don't have
any great solutions right now. 

Andrew Bartlett