For this first version we just want recompilation in this case. In later versions, we'll make Tachyon itself support evicting data to disk, because there's no easy way Spark could know when to do that.

I agree that we should not use the same filename from multiple nodes -- I thought this patch isn't doing that. But more generally we should probably not allow Tachyon mode to be on with StorageLevel.replication set, since this is again an option we can add in Tachyon itself.