Hi Pablo,

Pablo Fernandez ha scritto:
> Hi,
> I've seen different behaviors in dCache xrootd door and the normal xrootd 
> daemon, and before rising a ticket in dCache I wanted to ask you about what 
> is normal and what's not.
> I've used an example of proof job that tries to access a set of files. First 
> the files were stored in dCache (and accessible via xrdcrp commands), and I 
> found errors accessing the file with the proof job. Afterwards I changed the 
> location of the files to the olbd storage instead, and that didn't return 
> errors accessing the files, it worked fine.

  Ok, I think you are the first guy trying to do that. PROOF was 
designed to get great advantage from the low latency of the xrootd 
server, but that does not mean in principle that it cannot be used.

  Just to be pedantic, anyway, olbd does not handle any storage, but it 
handles the server-server interactions in an xrootd cluster (2->262000 
servers), so I suppose you are speaking about xrootd storage in an 
xrootd cluster. If not, please correct me.

> The error returned by root for every file is:
> Srv err: Stat request requires open file.
> 01:42:23  3789 Mst-0 | Error in <TDSetElement::Lookup>: couldn't lookup 
> root://
> (as you may have guessed, grid017 is the dCache xrootd door, and I'm sure it 
> works because it can copy back that same file with xrdcp)
> And the error returned by the dCache xrootd door is (again for each file):
> LogicalStream(localPort=1094 SID=256)  got new request from dispatcher 
> org.dcache.xrootd.protocol.messages.StatRequest
> Xrootd-Error-Response: ErrorNr=3004 ErrorMsg=Stat request requires open file.
> Xrootd-Response-Thread: sending response 
> org.dcache.xrootd.protocol.messages.ErrorResponse(SID=256)

  I cannot help you much here. If the error message is not misleading, 
this looks like a bug in the xrootd door. Stat is supposed to work for 
not opened files (otherwise it makes no sense), so I suppose you should 
report it to the dcache developers.

> So, the error means that a "stat" operation was sent before opening the file. 
> If the same access attempt succedes on a normal xrootd daemon and fails on 
> dCache, what do you think? Is is xrootd daemon too permissive or dCache too 
> restrictive?

  Well, the xrootd protocol is very clear, it's not a matter of 
permissions or restrictions, at least for the Stat request. But I know 
that there should be fixes for the dcache xrootd door.


> Thanks,
> Pablo