| > There are two Mac volumes, one on a NT box, a second on a VAX running
> PATHWORKS for Mac.
>
> A Mac has both volumes mounted and does a drag and drop from the NT to
> the VAX. How does the network packets flow? Do they pass through the
> Mac?
Yup.
If you need _EXACT_ details, then put a sniffer on the wire, and get a
copy of Inside AppleTalk, Second Edition to interpret what you are
seeing, but in broad general terms here is what happens:
Mac fetches the file attributes from the source file.
Mac creates an output file with the attribute information just fetched.
Mac opens source file data fork.
Mac opens destination file data fork.
Mac pre-allocates enough space in the output file to hold the contents
of the input file.
Mac reads data from the source.
Mac writes data to the destination.
Repeat reading/writing until data fork is totally copied.
Truncate destination file to free up any excess space allocated.
Close source data fork
Close destination data fork.
Repeat above for Resource fork.
Repeat above for each file to be copied.
----
The only shortcut copy operation is if the source and destination are
on the same server. Then there is a command that can be sent to the
server to request that it do the copy internal to itself. This can be
on the same volume (such as a Duplicate Command/D request or a drag and
drop with the Option key held), or it can be between to volumes both
served by the same server.
All other copy operations require the Mac doing the Drag and Drop to be
involved in each read and write of data.
Bob Harris
PS. In case you take me seriously about using a sniffer, there is an
on-line copy of Inside AppleTalk, Second Edition available at the
following URL:
<http://devworld.apple.com/ngs/lpp/adrpub/docs/dev/opentransport/reference.html>
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