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On 19Aug2006, at 18:02 , Fons Rademakers wrote: > Hi Andy, Fabrizio, > > what we really urgently would like to have is an xrootd command > that takes as input a vector of generic xrootd urls and returns a > vector with resolved urls (including multiple urls in case the same > file exists on more than one leaf node). Of course the first time > this will take some time since the head node will have to ask the > leaf nodes, but from then on this info lives in the xrootd head > node cache, so it should be very quick. We need the final location > in PROOF to submit work packets with priority to the nodes that > have the data local. > > Can you tell me if this feature is possible and if we can get it soon? I would like to understand what you are really asking for. When you say you want a "resolved url", do you mean a path to the physical cache server(s) that currently caches the file? And when you say "nodes that have the data local", do you intend to run an xrootd cache server on each compute node? Or does "local" mean, on the same LAN? My understanding (probably out of date), is that an Xrootd cache node is free to remove a file from its cache at any time, unless somebody has taken a specific action to pin it in the cache. Statistically, it is likely that it will still be cached when PROOF tries to access it, but there is no promise. So the "resolved urls" will at best be advisory. Has that changed? -- Gregory J. Sharp email: [log in to unmask] Wilson Synchrotron Laboratory url: http://www.lepp.cornell.edu/ ~gregor Cornell University ph: +1 607 255 4882 Ithaca, NY 14853 fax: +1 607 255 8062