</sect1>
- <sect1 id="example-watchdog">
- <title>Watchdog Configuration Example</title>
+ <sect1 id="example-watchdog">
+ <title>Watchdog Configuration Example</title>
+ <para>
+ This tutrial explains the simple way to try "Watchdog".
+ What you need is 2 Linux boxes on which <productname>
+ Pgpool-II</productname> is installed and a PostgreSQL
+ on the same machine or in the other one. it is enough
+ that 1 node for backend exists.
+ You can use on memory query cache with <productname>
+ Pgpool-II</productname> in any mode: replication mode,
+ master/slave mode and raw mode.
+ </para>
+ <para>
+ This example uses use "osspc16" as an Active node and
+ "osspc20" as a Standby node. "Someserver" means one of them.
+ </para>
+
+ <sect2 id="example-watchdog-configuration">
+ <title>Common configurations</title>
<para>
- Watchdog configuration.
+ Set the following parameters in both of active and standby nodes.
</para>
- </sect1>
+
+ <sect3 id="example-watchdog-config-enable">
+ <title>Enabling watchdog</title>
+ <para>
+ First of all, set <xref linkend="guc-use-watchdog"> to on.
+ <programlisting>
+use_watchdog = on
+ # Activates watchdog
+ </programlisting>
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-config-upstream">
+ <title>Configure Up stream servers</title>
+ <para>
+ Specify the up stream servers (e.g. application servers).
+ Leaving it blank is also fine.
+ <programlisting>
+trusted_servers = ''
+ # trusted server list which are used
+ # to confirm network connection
+ # (hostA,hostB,hostC,...)
+ </programlisting>
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-config-wd-comm">
+ <title>Watchdog Communication</title>
+ <para>
+ Specify the TCP port number for watchdog communication.
+ <programlisting>
+wd_port = 9000
+ # port number for watchdog service
+ </programlisting>
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-config-wd-vip">
+ <title>Virtual IP</title>
+ <para>
+ Specify the IP address to be used as a virtual IP address
+ in the <xref linkend="guc-delegate-IP">.
+ <programlisting>
+delegate_IP = '133.137.177.143'
+ # delegate IP address
+ </programlisting>
+ </para>
+ <note>
+ <para>
+ Make sure the IP address configured as a Virtual IP should be
+ free and is not used by any other machine.
+ </para>
+ </note>
+ </sect3>
+ </sect2>
+
+ <sect2 id="example-watchdog-configuration-each-server">
+ <title>Individual Server Configurations</title>
+ <para>
+ Next, set the following parameters for each <productname>
+ Pgpool-II</productname>.
+ Specify <xref linkend="guc-other-pgpool-hostname">,
+ <xref linkend="guc-other-pgpool-port"> and
+ <xref linkend="guc-other-wd-port"> with the values of
+ other <productname>Pgpool-II</productname> server values.
+ </para>
+
+ <sect3 id="example-watchdog-configuration-active-server">
+ <title>Active (osspc16) Server configurations</title>
+ <para>
+ <programlisting>
+other_pgpool_hostname0 = 'osspc20'
+ # Host name or IP address to connect to for other pgpool 0
+other_pgpool_port0 = 9999
+ # Port number for othet pgpool 0
+other_wd_port0 = 9000
+ # Port number for othet watchdog 0
+ </programlisting>
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-configuration-standby-server">
+ <title>Standby (osspc20) Server configurations</title>
+ <para>
+ <programlisting>
+other_pgpool_hostname0 = 'osspc16'
+ # Host name or IP address to connect to for other pgpool 0
+other_pgpool_port0 = 9999
+ # Port number for othet pgpool 0
+other_wd_port0 = 9000
+ # Port number for othet watchdog 0
+ </programlisting>
+ </para>
+ </sect3>
+ </sect2>
+
+ <sect2 id="example-watchdog-start-server">
+ <title>Starting <productname>Pgpool-II</productname></title>
+ <para>
+ Start <productname>Pgpool-II</productname> on each servers from
+ <literal>root</literal> user with <literal>"-n"</literal> switch
+ and redirect log messages into pgpool.log file.
+ </para>
+
+ <sect3 id="example-watchdog-start-active-server">
+ <title>Starting pgpool in Active server (osspc16)</title>
+ <para>
+ First start the <productname>Pgpool-II</productname> on Active server.
+ <programlisting>
+[user@osspc16]$ su -
+[root@osspc16]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
+ </programlisting>
+ Log messages will show that <productname>Pgpool-II</productname>
+ has the virtual IP address and starts watchdog process.
+ <programlisting>
+LOG: I am announcing my self as master/coordinator watchdog node
+LOG: I am the cluster leader node
+DETAIL: our declare coordinator message is accepted by all nodes
+LOG: I am the cluster leader node. Starting escalation process
+LOG: escalation process started with PID:59449
+<emphasis>LOG: watchdog process is initialized
+LOG: watchdog: escalation started
+LOG: I am the master watchdog node</emphasis>
+DETAIL: using the local backend node status
+ </programlisting>
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-start-standby-server">
+ <title>Starting pgpool in Standby server (osspc20)</title>
+ <para>
+ Now start the <productname>Pgpool-II</productname> on Standby server.
+ <programlisting>
+[user@osspc20]$ su -
+[root@osspc20]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
+ </programlisting>
+ Log messages will show that <productname>Pgpool-II</productname>
+ has joind the watchdog cluster as standby watchdog.
+ <programlisting>
+LOG: watchdog cluster configured with 1 remote nodes
+LOG: watchdog remote node:0 on Linux_osspc16_9000:9000
+LOG: interface monitoring is disabled in watchdog
+LOG: IPC socket path: "/tmp/.s.PGPOOLWD_CMD.9000"
+LOG: watchdog node state changed from [DEAD] to [LOADING]
+LOG: new outbond connection to Linux_osspc16_9000:9000
+LOG: watchdog node state changed from [LOADING] to [INITIALIZING]
+LOG: watchdog node state changed from [INITIALIZING] to [STANDBY]
+<emphasis>
+LOG: successfully joined the watchdog cluster as standby node
+DETAIL: our join coordinator request is accepted by cluster leader node "Linux_osspc16_9000"
+LOG: watchdog process is initialized
+</emphasis>
+ </programlisting>
+ </para>
+ </sect3>
+ </sect2>
+
+ <sect2 id="example-watchdog-try">
+ <title>Try it out</title>
+ <para>
+ Confirm to ping to the virtual IP address.
+ <programlisting>
+[user@someserver]$ ping 133.137.177.142
+PING 133.137.177.143 (133.137.177.143) 56(84) bytes of data.
+64 bytes from 133.137.177.143: icmp_seq=1 ttl=64 time=0.328 ms
+64 bytes from 133.137.177.143: icmp_seq=2 ttl=64 time=0.264 ms
+64 bytes from 133.137.177.143: icmp_seq=3 ttl=64 time=0.412 ms
+ </programlisting>
+ Confirm if the Active server which started at first has the virtual IP address.
+ <programlisting>
+[root@osspc16]# ifconfig
+eth0 ...
+
+eth0:0 inet addr:133.137.177.143 ...
+
+lo ...
+ </programlisting>
+ Confirm if the Standby server which started not at first doesn't have the virtual IP address.
+ <programlisting>
+[root@osspc20]# ifconfig
+eth0 ...
+
+lo ...
+ </programlisting>
+
+ Try to connect PostgreSQL by "psql -h delegate_IP -p port".
+ <programlisting>
+[user@someserver]$ psql -h 133.137.177.142 -p 9999 -l
+ </programlisting>
+ </para>
+ </sect2>
+
+ <sect2 id="example-watchdog-vip-switch">
+ <title>Switching virtual IP</title>
+ <para>
+ Confirm how the Standby server works when the Active server can't provide its service.
+ Stop <productname>Pgpool-II</productname> on the Active server.
+ <programlisting>
+[root@osspc16]# {installed_dir}/bin/pgpool stop
+ </programlisting>
+
+ Then, the Standby server starts to use the virtual IP address. Log shows:
+
+ <programlisting>
+<emphasis>
+LOG: remote node "Linux_osspc16_9000" is shutting down
+LOG: watchdog cluster has lost the coordinator node
+</emphasis>
+LOG: watchdog node state changed from [STANDBY] to [JOINING]
+LOG: watchdog node state changed from [JOINING] to [INITIALIZING]
+LOG: I am the only alive node in the watchdog cluster
+HINT: skiping stand for coordinator state
+LOG: watchdog node state changed from [INITIALIZING] to [MASTER]
+LOG: I am announcing my self as master/coordinator watchdog node
+LOG: I am the cluster leader node
+DETAIL: our declare coordinator message is accepted by all nodes
+<emphasis>
+LOG: I am the cluster leader node. Starting escalation process
+LOG: watchdog: escalation started
+</emphasis>
+LOG: watchdog escalation process with pid: 59551 exit with SUCCESS.
+ </programlisting>
+
+ Confirm to ping to the virtual IP address.
+ <programlisting>
+[user@someserver]$ ping 133.137.177.142
+PING 133.137.177.143 (133.137.177.143) 56(84) bytes of data.
+64 bytes from 133.137.177.143: icmp_seq=1 ttl=64 time=0.328 ms
+64 bytes from 133.137.177.143: icmp_seq=2 ttl=64 time=0.264 ms
+64 bytes from 133.137.177.143: icmp_seq=3 ttl=64 time=0.412 ms
+ </programlisting>
+
+ Confirm that the Active server doesn't use the virtual IP address any more.
+ <programlisting>
+[root@osspc16]# ifconfig
+eth0 ...
+
+lo ...
+ </programlisting>
+
+ Confirm that the Standby server uses the virtual IP address.
+ <programlisting>
+[root@osspc20]# ifconfig
+eth0 ...
+
+eth0:0 inet addr:133.137.177.143 ...
+
+lo ...
+ </programlisting>
+
+ Try to connect PostgreSQL by "psql -h delegate_IP -p port".
+ <programlisting>
+[user@someserver]$ psql -h 133.137.177.142 -p 9999 -l
+ </programlisting>
+
+ </para>
+ </sect2>
+
+ <sect2 id="example-watchdog-more">
+ <title>More</title>
+
+ <sect3 id="example-watchdog-more-lifecheck">
+ <title>Lifecheck</title>
+ <para>
+ There are the parameters about watchdog's monitoring.
+ Specify the interval to check <xref linkend="guc-wd-interval">,
+ the count to retry <xref linkend="guc-wd-life-point">,
+ the qyery to check <xref linkend="guc-wd-lifecheck-query"> and
+ finaly the type of lifecheck <xref linkend="guc-wd-lifecheck-method">.
+ <programlisting>
+wd_lifecheck_method = 'query'
+ # Method of watchdog lifecheck ('heartbeat' or 'query' or 'external')
+ # (change requires restart)
+wd_interval = 10
+ # lifecheck interval (sec) > 0
+wd_life_point = 3
+ # lifecheck retry times
+wd_lifecheck_query = 'SELECT 1'
+ # lifecheck query to pgpool from watchdog
+ </programlisting>
+
+ </para>
+ </sect3>
+
+ <sect3 id="example-watchdog-more-vip-switching">
+ <title>Switching virtual IP address</title>
+ <para>
+ There are the parameters for switching the virtual IP address.
+ Specify switching commands <xref linkend="guc-if-up-cmd">,
+ <xref linkend="guc-if-down-cmd">, the path to them
+ <xref linkend="guc-if-cmd-path">, the command executed after
+ switching to send ARP request <xref linkend="guc-arping-cmd">
+ and the path to it <xref linkend="guc-arping-path">.
+ <programlisting>
+ifconfig_path = '/sbin'
+ # ifconfig command path
+if_up_cmd = 'ifconfig eth0:0 inet $_IP_$ netmask 255.255.255.0'
+ # startup delegate IP command
+if_down_cmd = 'ifconfig eth0:0 down'
+ # shutdown delegate IP command
+
+arping_path = '/usr/sbin' # arping command path
+
+arping_cmd = 'arping -U $_IP_$ -w 1'
+ </programlisting>
+ You can also use the custom scripts to bring up and bring down the
+ virtual IP using <xref linkend="guc-wd-escalation-command"> and
+ <xref linkend="guc-wd-de-escalation-command"> configurations.
+ </para>
+ </sect3>
+
+ </sect2>
+ </sect1>
<sect1 id="example-AWS">
<title>AWS Configuration Example</title>
projects / pgpool2.git / commitdiff