Cannot migrate DB due to "getaddrinfo: Name or service not known"

I am using Rails 2.2.2 and try to do a DB migration, but got the following error. I am using Centos 5.4. Can someone give me a clue?

rake db:migrate RAILS_ENV="production"

rake aborted! getaddrinfo: Name or service not known

(See full trace by running task with --trace) [current]$ rake db:migrate RAILS_ENV="production" --trace

** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment rake aborted! getaddrinfo: Name or service not known /usr/lib/ruby/1.8/drb/drb.rb:865:in `initialize' /usr/lib/ruby/1.8/drb/drb.rb:865:in `open' /usr/lib/ruby/1.8/drb/drb.rb:865:in `open_server' /usr/lib/ruby/1.8/drb/drb.rb:759:in `open_server' /usr/lib/ruby/1.8/drb/drb.rb:757:in `each' /usr/lib/ruby/1.8/drb/drb.rb:757:in `open_server' /usr/lib/ruby/1.8/drb/drb.rb:1339:in `initialize' /usr/lib/ruby/1.8/drb/drb.rb:1627:in `new' /usr/lib/ruby/1.8/drb/drb.rb:1627:in `start_service' /var/www/apps/arts/releases/20100227000015/vendor/plugins/backgroundrb/ lib/backgroundrb.rb:67:in `init' /var/www/apps/arts/releases/20100227000015/vendor/plugins/backgroundrb/ lib/middleman_rails_init.rb:11:in `init' /var/www/apps/arts/releases/20100227000015/vendor/plugins/backgroundrb/ lib/middleman_rails_init.rb:14 /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' /usr/lib64/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/ dependencies.rb:155:in `require' /var/www/apps/arts/releases/20100227000015/vendor/plugins/backgroundrb/ init.rb:2:in `evaluate_init_rb' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin.rb:103:in `evaluate_init_rb' /usr/lib64/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/ core_ext/kernel/reporting.rb:11:in `silence_warnings' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin.rb:99:in `evaluate_init_rb' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin.rb:44:in `load' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin/loader.rb: 33:in `load_plugins' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin/loader.rb: 32:in `each' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/rails/plugin/loader.rb: 32:in `load_plugins' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb:323:in `load_plugins' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb:160:in `process' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb:112:in `send' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/initializer.rb:112:in `run' /var/www/apps/arts/releases/20100227000015/config/environment.rb:162 /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' /usr/lib64/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/ dependencies.rb:153:in `require' /usr/lib64/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/ dependencies.rb:521:in `new_constants_in' /usr/lib64/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/ dependencies.rb:153:in `require' /usr/lib64/ruby/gems/1.8/gems/rails-2.2.2/lib/tasks/misc.rake:3 /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `call' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `execute' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `each' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `execute' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:597:in `invoke_with_call_chain' /usr/lib/ruby/1.8/monitor.rb:238:in `synchronize' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:607:in `invoke_prerequisites' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `each' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:604:in `invoke_prerequisites' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:596:in `invoke_with_call_chain' /usr/lib/ruby/1.8/monitor.rb:238:in `synchronize' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:583:in `invoke' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2051:in `invoke_task' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `each' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2023:in `top_level' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2001:in `run' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:1998:in `run' /usr/lib64/ruby/gems/1.8/gems/rake-0.8.7/bin/rake:31 /usr/bin/rake:19:in `load' /usr/bin/rake:19

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