I'm surprised that the copying bottleneck seems to have been entirely at the target rather than the source. Is that because there were multiple copies of the source?

I've had to employ the horrible hack of iscsi from compute nodes, raided and re-exported, but it's not what I'd have tried to use first. The article doesn't mention the possibility of just spinning up a parallel filesystem on compute node local disks (assuming they have disks); I wonder if that was ruled out. I don't have a good feeling for the numbers, but I'd have tried OrangeFS on a good number of nodes initially.

By the way, it's been pointed out that RAM disk is relatively slow, if in the context of data rates rather than metadata <http://mvapich.cse.ohio-state.edu/static/media/publications/....