// app/config/parameters.ini
[parameters]
    ; Symfonys database
    db1_driver="pdo_pgsql"
    db1_host="my.server.com"
    db1_name="dbname"
    db1_user="user"
    db1_password="pass"

    ; second database
    db2_driver="pdo_pgsql"
    db2_host="my.server.com"
    db2_name="dbname"
    db2_user="user"
    db2_password="pass"


// app/config/config.yml
# Doctrine Configuration
doctrine:
    dbal:
        default_connection:        db1
        connections:
            db1:
                driver:   %db1_driver%
                host:     %db1_host%
                dbname:   %db1_name%
                user:     %db1_user%
                password: %db1_password%
            db2:
                driver:   %db2_driver%
                host:     %db2_host%
                dbname:   %db2_name%
                user:     %db2_user%
                password: %db2_password%

    orm:
        auto_generate_proxy_classes: %kernel.debug%
        default_entity_manager:      db1
        entity_managers:
            default:
                connection:         db1
                mappings:
                    AcmeMyBundle:  ~
            db2:
                connection:         db2
                mappings:
                    AcmeMyBundle: ~

// from the console
php app/console doctrine:mapping:convert yml ./src/Acme/MyBundle/Resources/config/doctrine/metadata/orm --from-database --force -em="db2"

// result
[InvalidArgumentException]
The file "/var/virtual-hosts/symfony/trunk/app/config/config_db2.yml" does not exist.