ooodragon:

My local computer (two titan xps) suffer less from HDD speed’s bottleck
whereas my server with eight, or twenty rtx 2080ti suffers a lot from HDD…
Would there possibly a reason for this?


Your server might need to load much more data to feed the GPUs, so that the data loading bottleneck might be more serious in this case. I would generally assume that an HHD could create a bottleneck even in a single-GPU setup.



 ooodragon:

And I also heard from coworkers and num_worker =< 8 is always more than enough because setting more workers can bring another bottleneck when distributing the loader’s works. Is this also true?


I’m not sure you can define a hard threshold of e.g. 8 workers and it should depend on the system you are using, but your coworkers are correct: too many workers might degrade the performance again so you would have to find the “sweet spot”.