/usr/share/doc/slony1-2-doc/adminguide/stmtfailover.html

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>SLONIK FAILOVER</H1
><DIV
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><A
NAME="AEN8225"
></A
><H2
>Name</H2
>FAILOVER&nbsp;--&nbsp; Fail a broken replication set over to a backup node
    </DIV
><DIV
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><A
NAME="AEN8228"
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><H2
>Synopsis</H2
><P
><TT
CLASS="COMMAND"
>FAILOVER (options);</TT
></P
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><A
NAME="AEN8231"
></A
><H2
>Description</H2
><P
>     The <TT
CLASS="COMMAND"
>FAILOVER</TT
> command causes the backup node to take over all sets
     that currently originate on the failed
     node. <SPAN
CLASS="APPLICATION"
>slonik</SPAN
> will contact all other
     direct subscribers of the failed node to determine which node has
     the highest sync status for each set. If another node has a
     higher sync status than the backup node, the replication will
     first be redirected so that the backup node replicates against
     that other node, before assuming the origin role and allowing
     update activity.
    </P
><P
>     After successful failover, all former direct subscribers of the
     failed node become direct subscribers of the backup node. The
     failed node is abandoned, and can and should be removed from the
     configuration with <A
HREF="stmtdropnode.html"
>SLONIK DROP NODE</A
>.
    </P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
> ID = ival </TT
></DT
><DD
><P
> ID of the failed node</P
></DD
><DT
><TT
CLASS="LITERAL"
> BACKUP NODE = ival </TT
></DT
><DD
><P
> Node ID of the node that will take over all
      sets originating on the failed node</P
></DD
></DL
></DIV
><P
> This uses <A
HREF="function.failednode-integer-integer.html"
>schemadocfailednode(integer, integer)</A
>. </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8251"
></A
><H2
>Example</H2
><PRE
CLASS="PROGRAMLISTING"
>FAILOVER (
   ID = 1,
   BACKUP NODE = 2
);
    </PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8254"
></A
><H2
> Locking Behaviour </H2
><P
> Exclusive locks on each replicated table will be taken out
    on both the new origin node as replication triggers are changed.
    If the new origin was not completely up to date, and replication
    data must be drawn from some other node that is more up to date,
    the new origin will not become usable until those updates are
    complete. </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8257"
></A
><H2
> Dangerous/Unintuitive Behaviour </H2
><P
> This command will abandon the status of the failed
    node.  There is no possibility to let the failed node join the
    cluster again without rebuilding it from scratch as a slave.  If
    at all possible, you would likely prefer to use <A
HREF="stmtmoveset.html"
>SLONIK MOVE SET</A
> instead, as that does
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> abandon the failed node.
    </P
><P
> If there are many nodes in a cluster, and failover includes
    dropping out additional nodes (<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>e.g.</I
></SPAN
> when it
    is necessary to treat <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> nodes at a site
    including an origin as well as subscribers as failed), it is
    necessary to carefully sequence the actions.
    </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8265"
></A
><H2
> Version Information </H2
><P
> This command was introduced in <SPAN
CLASS="PRODUCTNAME"
>Slony-I</SPAN
> 1.0 </P
><P
> In version 2.0, the default <TT
CLASS="ENVAR"
>BACKUP NODE</TT
> value of 1 was removed, so it is mandatory to provide a value for this parameter.</P
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slony1-2-doc 2.0.7-3build1 / usr / share / doc / slony1-2-doc / adminguide / stmtfailover.html
