copy offload for SMB?

David Disseldorp ddiss at
Fri Feb 22 03:30:21 MST 2013

On Thu, 21 Feb 2013 21:49:35 -0800
Richard Sharpe <realrichardsharpe at> wrote:

> 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.

Yes, see the smb2.ioctl.copy_chunk_* torture tests.

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

2k8 doesn't use it for copies initiated via Explorer, 2k12 does though.
See source3/smbd/smb2_ioctl_network_fs.c for the Samba implementation.

Cheers, David

More information about the samba-technical mailing list