What is maximum SMB2 IOCTL(FSCTL_GET_SHADOW_COPY) response size.

Volker Lendecke Volker.Lendecke at SerNet.DE
Tue Jan 20 13:25:32 MST 2015

On Tue, Jan 20, 2015 at 09:21:57AM -0800, Hemanth Thummala wrote:
> Hi Volker,
> I found hard limit(512) on the number of shadow copies(MaxShadowCopies)
> that windows server can keep. With 512 snapshots, IOCTL response is not
> going to exceed 32K. I don't think client will behave differently in this
> case even after enable or disable the large MTU support.
> Please correct me if I am wrong.

Sure. I did not know about that limit. Sorry, I don't have
more ideas then except to test with latest Samba. You might
want to test on a standard Linux and simulate the snapshots
somehow. If that works, comparing the traces might point out
some minimal patch that can be applied to 3.6.


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