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diff --git a/doc/guide.tex b/doc/guide.tex index f656d932..dd2775f4 100644 --- a/doc/guide.tex +++ b/doc/guide.tex @@ -721,38 +721,118 @@ Each \ejabberd{} node have following modules: \subsubsection{Router} -This module is the main router of \Jabber{} packets on each node. It routes -them based on their destinations domains. It has two tables: local and global -routes. First, domain of packet destination searched in local table, and if it -found, then the packet is routed to appropriate process. If no, then it -searches in global table, and is routed to the appropriate \ejabberd{} node or -process. If it does not exists in either tables, then it sent to the S2S -manager. +This module is the main router of \Jabber{} packets on each node. It +routes them based on their destinations domains. It uses a global +routing table. A domain of packet destination is searched in the +routing table, and if it is found, then the packet is routed to +appropriate process. If no, then it is sent to the S2S manager. \subsubsection{Local Router} -This module routes packets which have a destination domain equal to this server -name. If destination JID has a non-empty user part, then it routed to the -session manager, else it is processed depending on it's content. +This module routes packets which have a destination domain equal to +this server name. If destination JID has a non-empty user part, then +it is routed to the session manager, else it is processed depending on +its content. \subsubsection{Session Manager} -This module routes packets to local users. It searches for what user resource -packet must be sended via presence table. If this resource is connected to -this node, it is routed to C2S process, if it connected via another node, then -the packet is sent to session manager on that node. +This module routes packets to local users. It searches to what user +resource a packet must be sent via a presence table. Then packet is +either routed to appropriate C2S process, or stored in offline +storage, or bounced back. \subsubsection{S2S Manager} -This module routes packets to other \Jabber{} servers. First, it checks if an -open S2S connection from the domain of the packet source to the domain of -packet destination already exists. If it is open on another node, then it -routes the packet to S2S manager on that node, if it is open on this node, then -it is routed to the process that serves this connection, and if a connection -does not exist, then it is opened and registered. +This module routes packets to other \Jabber{} servers. First, it +checks if an opened S2S connection from the domain of the packet +source to the domain of packet destination is existing. If it is +existing, then the S2S manager routes the packet to the process +serving this connection, else a new connection is opened. + + +\subsection{How to setup ejabberd cluster} +\label{sec:cluster} + +Suppose you already setuped ejabberd on one of machines (\term{first}), and +you need to setup another one to make \ejabberd{} cluster. Then do +following steps: + +\begin{enumerate} +\item Copy \verb|~ejabberd/.erlang.cookie| file from \term{first} to + \term{second}. + + (alt) You can also add ``\verb|-cookie content_of_.erlang.cookie|'' + option to all ``\shell{erl}'' commands below. + +\item On \term{second} run under `\term{ejabberd}' user in a directory + where ejabberd will work later the following command: + +\begin{verbatim} +erl -sname ejabberd \ + -mnesia extra_db_nodes "['ejabberd@first']" \ + -s mnesia +\end{verbatim} + + This will start mnesia serving same DB as \node{ejabberd@first}. + You can check this running ``\verb|mnesia:info().|'' command. You + should see a lot of remote tables and a line like the following: + +\begin{verbatim} +running db nodes = [ejabberd@first, ejabberd@second] +\end{verbatim} + + +\item Now run the following in the same ``\shell{erl}'' session: + +\begin{verbatim} +mnesia:change_table_copy_type(schema, node(), disc_copies). +\end{verbatim} + + This will create local disc storage for DB. + + (alt) Change storage type of `\term{scheme}' table to ``RAM and disc + copy'' on second node via web interface. + + +\item Now you can add replicas of various tables to this node with + ``\verb|mnesia:add_table_copy|'' or + ``\verb|mnesia:change_table_copy_type|'' as above (just replace + ``\verb|schema|'' with another table name and ``\verb|disc_copies|'' + can be replaced with ``\verb|ram_copies|'' or + ``\verb|disc_only_copies|''). + + What tables to replicate is very depend on your needs, you can get + some hints from ``\verb|mnesia:info().|'' command, by looking at + size of tables and default storage type for each table on 'first'. + + Replicating of table makes lookup in this table faster on this node, + but writing will be slower. And of course if machine with one of + replicas is down, other replicas will be used. + + Also section ``5.3 Table Fragmentation'' + \footahref{http://erlang.org/doc/r9c/lib/mnesia-4.1.4/doc/html/part_frame.html}{here} + can be useful. + + (alt) Same as in previous item, but for other tables. + + +\item Run ``\verb|init:stop().|'' or just ``\verb|q().|'' to exit from + erlang shell. This probably can take some time if mnesia is not yet + transfer and process all data it needed from \term{first}. + + +\item Now run ejabberd on \term{second} with almost the same config as + on \term{first} (you probably don't need to duplicate ``\verb|acl|'' + and ``\verb|access|'' options --- they will be taken from + \term{first}, and \verb|mod_muc| and \verb|mod_irc| should be + enabled only on one machine in cluster). +\end{enumerate} + +You can repeat these steps for other machines supposed to serve this +domain. \appendix{} |