[erlang-questions] Mnesia Backup/Fallback Problems With Schema

Gordon Guthrie <>
Fri Jun 8 10:47:10 CEST 2012


Folks

Having some problems with mnesia backups.

I have servers running with lots of tables for lots of site, so we use
a naming convention for the tables to separate the data:
site_1_table_1, ..., site_1_table_n
...
site_m_table_1, ..., site_m_table_n

I want to be able to backup individual sites and restore them - maybe
on the original machine, maybe on another one.

So I setup a checkpoint across a set of tables (site_1_table_1 to
site_1_table_n) and back it up.

The tables can be quite big so mnesia:restore/2 isn't practical and I
have to use mnesia:install_fallback - this is where I hit problems.

I get the error message:

     {error,{"Cannot install fallback",
              {"Cannot lookup",schema}}}

Ok, I figured it needs the schema to be backed up as well, so I then
build a checkpoint with the schema and the set of tables I want to
backup. But when I run that I get a different error:

     {error,{"Cannot install fallback",
              {already_exists,''}}}

So I am at a bit of a loss.

Does install_fallback only work with whole table backups?

Gordon



More information about the erlang-questions mailing list