On 12/14/2011 02:59 PM, Jeremy Allison wrote:
On Wed, Dec 14, 2011 at 02:22:07PM -0500, Ric Wheeler wrote:
Back at LinuxCon Prague, we talked about the new NFS and SCSI
commands that let us offload copy operations to a storage device
(like an NFS server or storage array).
This got new life in the virtual machine world where you might want
to clone bulky guest files or ranges of blocks and was driven
through the standards bodies by vmware, microsoft and some of the
major storage vendors. Windows8 has this functionality fully coded
and integrated in the GUI, I assume vmware also uses it and there
are some vendors who announced support at the SNIA SDC conference.
We had an active thread a couple of years back that came out of the
reflink work and, at the time, there seemed to be moderately
positive support for adding a new system call that would fit this
use case (Joel Becker's copyfile()).
Can we resurrect this effort? Is copyfile() still a good way to go,
or should we look at other hooks?
Windows uses a COPYCHUNK call, which specifies the
following parameters:
Definition of a copy "chunk":
hyper source_off;
hyper target_off;
uint32 length;
and an array of these chunks which is passed
into their kernel.
This is what we have to implement in Samba.
Jeremy.
This is a public pointer to the draft NFS proposal:
http://tools.ietf.org/id/draft-lentini-nfsv4-server-side-copy-06.txt
The T10 site has some click through that I was not too happy about agreeing to.
NetApp (Fred Knight) had some nice presentations that he presented about how
SCSI does this in two different ways...
Ric
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