How to add a node to an mnesia cluster?

转载：http://stackoverflow.com/questions/787755/how-to-add-a-node-to-an-mnesia-cluster

Start your new node (

b@node

)

erl -sname b -mnesia dir '"/path/to/storage"' -s mnesia

. This starts a new ram_copes node called

b@node

.

On your original node (

a@node

), at the erlang prompt execute

mnesia:change_config(extra_db_nodes, ['b@node']).

This will cause the original node to connect

b

to the mnesia cluster. At this point,

b@node

has joined the cluster but only has a copy of the schema.

To make new the node

b@node

capable of storing disc copies, we need to change the schema table type on

b@node

from

ram_copies

to

disc_copies

. Run

mnesia:change_table_copy_type(schema, 'b@node', disc_copies).

on any node.

b@node

only has a copy of the schema at this point. To copy all the tables from

a@node

to

b@node

and maintain table types, you can run:

[{Tb, mnesia:add_table_copy(Tb, node(), Type)}
|| {Tb, [{'a@node', Type}]} <- [{T, mnesia:table_info(T, where_to_commit)}
|| T <- mnesia:system_info(tables)]].

This command may take a while to execute as it will copy the contents of each table over the network.

b@node

is now an exact replica of

a@node

. You could modify that statement - replace the

Type

variable with

disc_only_copies

in the call to

mnesia:add_table_copy/3

in order to copy the tables but ensure they're on disc only.