Mnesia can't create disc copy

Questions / Help
1

I’m running into problem with mnesia table creation. When I’ve called :mnesia.create_table/2 with option disc_only_copies: [Node.self()] I’ve got bad_type error. So I’ve tried :mnesia.change_table_copy_type/3. With bigger success. Now I’m getting {:aborted, {:has_no_disc, :nonode@nohost}} error.

I didn’t specify any host name.
Platform: Mac OS X, M2 CPU
Erlang: 26.0.2
Elixir: 1.15.5

Code snippet:

alias :mnesia, as: Mnesia
Mnesia.stop()
Mnesia.create_schema([Node.self()])
Mnesia.start()

Mnesia.create_table(Pulse,[
    type: :set,
#    disc_only_copies: [Node.self()],
    record_name: Pulse,
    attributes: @record_fields
])

Mnesia.change_table_copy_type(Pulse, Node.self(), :disc_copies)

Line commented out was used when I was creating table with disc persistence.

1 Like
2

Is the directory where you’re running mnesia writable?

You may also want to try running with the environment variable ERL_FLAGS="-mnesia debug trace" set. That way mnesia will give you information about what it’s doing. (-mnesia debug verbose will be less noisy)

2 Likes
3

I’ve had this in my config. Which caused the bug. Right after I’ve removed mnesia config it just works. I’ve forgotten about it when I was testing elixir libraries interacting with mnesia.

config :mnesia,
  dir: ".mnesia/#{Mix.env()}/#{node()}"
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