[erlang-questions] mnesia async vs sync

[Roberto Ostinelli]

Dear list,
To my understanding the main difference between the mnesia sync and async activities is that the latter does not wait for a confirmation from all the nodes that a write has been successful before returning.

Thus, I would expect that the write speed of an async activity remains similar even when the number of node increases; however according to my benchmarks this is not true. The write speed decreases when the number of nodes increase.

Can someone enlighten me of why this is?

Thank you in advance. 
r.