Unexpected behaviour with mnesia - not actually durable?

[Exadra37]

So this lost of data when you kill Mnesia is not due at all to Mnesia itself, but instead to how the file is open to write to the disk,

Please see this post that also as a script demonstrating the same issue when writing directly to the disk from a script:

Mnesia with Memento lost all records for all tables

The BEAM indeed has a default of 2 seconds to write data to the disk when the file is open with the defaults for delayed_write, as per docs : delayed_write The same as {delayed_write, Size, Delay} with reasonable default values for Size and Delay (roughly some 64 KB, 2 seconds). Now I just need to do some tests with a simple Elixir script and see if this “insane” default can be optimized with {delayed_write, Size, Delay} from 2 seconds to something like 2 or 20 ms, because 2 seconds is an …