Watchdog Configuration Example

8.2.1.1. Enabling watchdog

First of all, set use_watchdog to on.

use_watchdog = on
                                        # Activates watchdog
     

8.2.1.2. Configure Up stream servers

Specify the up stream servers (e.g. application servers). Leaving it blank is also fine.

trusted_servers = ''
                                        # trusted server list which are used
                                        # to confirm network connection
                                        # (hostA,hostB,hostC,...)
    

8.2.1.3. Watchdog Communication

Specify the TCP port number for watchdog communication.

wd_port = 9000
                                        # port number for watchdog service
    

8.2.1.4. Virtual IP

Specify the IP address to be used as a virtual IP address in the delegate_IP .

delegate_IP = '133.137.177.143'
                                        # delegate IP address
     

8.2.2.1. Active (osspc16) Server configurations

other_pgpool_hostname0 = 'osspc20'
                                        # Host name or IP address to connect to for other pgpool 0
other_pgpool_port0 = 9999
                                        # Port number for other pgpool 0
other_wd_port0 = 9000
                                        # Port number for other watchdog 0
    

8.2.2.2. Standby (osspc20) Server configurations

other_pgpool_hostname0 = 'osspc16'
                                        # Host name or IP address to connect to for other pgpool 0
other_pgpool_port0 = 9999
                                        # Port number for other pgpool 0
other_wd_port0 = 9000
                                        # Port number for other watchdog 0
    

8.2.3.1. Starting pgpool in Active server (osspc16)

First start the Pgpool-II on Active server.

[user@osspc16]$ su -
[root@osspc16]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
    

Log messages will show that Pgpool-II has the virtual IP address and starts watchdog process.

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
LOG:  watchdog process is initialized
LOG:  watchdog: escalation started
LOG:  I am the master watchdog node
DETAIL:  using the local backend node status
    

8.2.3.2. Starting pgpool in Standby server (osspc20)

Now start the Pgpool-II on Standby server.

[user@osspc20]$ su -
[root@osspc20]# {installed_dir}/bin/pgpool -n -f {installed_dir}/etc/pgpool.conf > pgpool.log 2>&1
    

Log messages will show that Pgpool-II has joined the watchdog cluster as standby watchdog.

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 outbound connection to Linux_osspc16_9000:9000
LOG:  watchdog node state changed from [LOADING] to [INITIALIZING]
LOG:  watchdog node state changed from [INITIALIZING] to [STANDBY]
     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
     
    

8.2.6.1. Lifecheck

There are the parameters about watchdog's monitoring. Specify the interval to check wd_interval and the type of lifecheck wd_lifecheck_method . The hearbeat method specify the time to detect a fault wd_heartbeat_deadtime , the port number to receive wd_heartbeat_port , the interval to send wd_heartbeat_keepalive , the IP address or hostname of destination heartbeat_destination<emphasis>0</emphasis> and finally the destination port number heartbeat_destination_port<emphasis>0</emphasis> .

wd_lifecheck_method = 'heartbeat'
                                    # Method of watchdog lifecheck ('heartbeat' or 'query' or 'external')
                                    # (change requires restart)
wd_interval = 10
                                    # lifecheck interval (sec) > 0
wd_heartbeat_port = 9694
                                    # Port number for receiving heartbeat signal
                                    # (change requires restart)
wd_heartbeat_keepalive = 2
                                    # Interval time of sending heartbeat signal (sec)
                                    # (change requires restart)
wd_heartbeat_deadtime = 30
                                    # Deadtime interval for heartbeat signal (sec)
                                    # (change requires restart)
heartbeat_destination0 = 'host0_ip1'
                                    # Host name or IP address of destination 0
                                    # for sending heartbeat signal.
                                    # (change requires restart)
heartbeat_destination_port0 = 9694
                                    # Port number of destination 0 for sending
                                    # heartbeat signal. Usually this is the
                                    # same as wd_heartbeat_port.
                                    # (change requires restart)
    

8.2.6.2. Switching virtual IP address

There are the parameters for switching the virtual IP address. Specify switching commands if_up_cmd , if_down_cmd , the path to them if_cmd_path , the command executed after switching to send ARP request arping_cmd and the path to it arping_path .

if_cmd_path = '/sbin'
                                    # path to the directory where if_up/down_cmd exists
if_up_cmd = 'ip addr add $_IP_$/24 dev eth0 label eth0:0'
                                    # startup delegate IP command
if_down_cmd = 'ip addr del $_IP_$/24 dev eth0'
                                    # shutdown delegate IP command

arping_path = '/usr/sbin'           # arping command path

arping_cmd = 'arping -U $_IP_$ -w 1'
    

You can also bring up and bring down the virtual IP using arbitrary scripts specified wd_escalation_command and wd_de_escalation_command parameters.