I tried this command also. It didn't work. It shows syntax again. Please see the supported commands in dovecot 2.0.9 version. This doesn't support replication also as per syntax, if i am not wrong. Please suggest me. 

[root@production ~]# doveadm backup -u kishore@test.org.com remote:vmail@production2.test.org.com
usage: doveadm [-Dv] [-f <formatter>] <command> [<args>]

  altmove      [-u <user>|-A] [-S <socket_path>] <search query>
  auth         [-a <auth socket path>] [-x <auth info>] <user> [<password>]
  config       [doveconf parameters]
  director     add|flush|map|remove|status
  dump         [-t <type>] <path>
  expunge      [-u <user>|-A] [-S <socket_path>] <search query>
  fetch        [-u <user>|-A] [-S <socket_path>] <fields> <search query>
  force-resync [-u <user>|-A] [-S <socket_path>] <mailbox>
  help         <cmd>
  import       [-u <user>|-A] [-S <socket_path>] <source mail location> <dest parent mailbox> <search query>
  kick         [-a <anvil socket path>] [-f] <user mask>[|]<ip/bits>
  log          find|reopen|test
  mailbox      create|delete|list|mutf7|rename|status|subscribe|unsubscribe
  penalty      [-a <anvil socket path>] [<ip/bits>]
  purge        [-u <user>|-A] [-S <socket_path>]
  pw           [-l] [-p plaintext] [-r rounds] [-s scheme] [-u user] [-V]
  reload
  search       [-u <user>|-A] [-S <socket_path>] <search query>
  sis          deduplicate|find
  stop
  user         [-a <userdb socket path>] [-x <auth info>] <user mask> [...]
  who          [-a <anvil socket path>] [-1] [<user mask>] [<ip/bits>]