copy offload for SMB?

Richard Sharpe realrichardsharpe at
Thu Feb 21 22:49:35 MST 2013

On Thu, Feb 21, 2013 at 6:39 PM, Christopher R. Hertel <crh at> wrote:
> On 02/21/2013 08:08 PM, Richard Sharpe wrote:
>> Hi folks,
>> Does Microsoft have support for doing copies locally on the server
>> when the source and destination are on the same server?
>> Eg: cp E:\some-path-1\some-file E:\some-path-2\
> Yes.  See [MS-SMB2] section, covering SRV_COPYCHUNK_COPY
>   "The SRV_COPYCHUNK_COPY packet is sent in an SMB2 IOCTL Request by
>   the client to initiate a server-side copy of data."

Thanks for that. It looks like the steps are:

1. Open the source file and send an FSCTL asking for a resume key.

2. Create the destination file.

3. Issue an FSCTL on the newly created destination file specifying the
resume key and the blocks to copy.

4. Close files.

Now to check if W2K08 sends such an FSCTL to see if it can get a resume key.

Richard Sharpe

More information about the samba-technical mailing list