Hi Pete,
> In this case "client" = xcp (or xrdcp, you ducked the naming question), is
> that correct?
Yes, I ducked it. I would vote for xrdcp to avoid name clashes.
> (a) Simply stops with an error message if one tries to do such a wildcarded
> copy via a load balancer instead of an actual dataserver. Can the
> client application determine this?
Yes, but that leads to non-determinsitic behaviour. One could shoose a
compromise and allow directory copies but not full wildcard copies. This
keeps the client somewhat simple because doing full wildcard copies is not
trivial.
> (b) Gives me what is actually there on disk instead of what might be
> out there in tertiary storage someplace.
True, but again not completely satisfying unless you are quite aware of
what you're doing.
> So what subtleties am I missing? (If I get a file being copied in at that
> moment I presumably get what is there at that point, just like with 'cp'.)
Correct.
> Since I may be going via the load-balancer to write the file, how do I
> create the "/some/path"? I have no idea in advance to which server I will be
> redirected. ("I" in this case being xcp/xrdcp.)
Writes are problematic. Generally, you don't need to know ahead of time.
You create the path once you get there.
Andy
