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> Does this refer to a partial return to the old planned data placement model, rather than PD2P driven placement? If so, I'm not sure, > based on my understanding of the data usage patterns, that that sounds like a good idea. It was decided by CREM few weeks ago to have a mixed model for some reason. > My understanding, based essentially on Graeme's GridPP 26 talk, is that a lot of data that was placed in a planned fashion was > never used. > PD2P seem to be a much more sensible system for a model in which the Tier 2 disk is primarily cache, not storage. > As far as I can see the key problem is that PD2P is not very aggressive about getting new, hot, interesting datasets replicated. > I'd have thought it would make sense to get copies of those 'hot' datasets on to as many Tier 2 disks as possible, as quickly as > possible, so as to make as many CPUs available for analysis as possible. part of the discussion was also to copy to T2s at first request. Still it remains unexplained why the UK is trailing behind so much. Other clouds don't seem to struggle as much to get data. Perhaps we should put more serious work in understanding that. cheers alessandra