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Hello Peter, > We just went through some of these things today at CNAF WRT gpfs (I > recognize this is what you are using here). The solutions are: > > a) use the cache filesystem to tie the three gpfs filesystems together > into one "namespace" to export (This is what is done at SLAC and most > of the other sites that have more than one filesystem/server.) See: > > http://xrootd.slac.stanford.edu/doc/mps_config/mps_config.htm > > (I _really_ need to provide a simple example of this.) Yes, it would be nice to have an example. I'll try to use mps on Tuesday. > b) Run one xrootd per gpfs filesystem (since they are o(8TB) each, this > probably isn't a disaster. Unfortunately I have only 2 GPFS fileservers and 3 disks so I cannot use this as a solution without loosing a disk. > The fundamental issue here is that gpfs is trying to do one of the things > that xrootd is trying to do, namely load balancing across the fileservers. > They aren't incompatible, but the part that gpfs doesn't do (allow the > separate filesystems to be treated as a single logical file space) has to be > dealt with some way. The choices are really (a) or (b) above. (Or _really_ > ugly solutions, like the current one being used by some of LHC experiments > where the location of the file on a particular filesystem is being managed > by an external catalog....) -- Gregory