CentOS 6.5下PostgreSQL 故障切换实现(2)

启动命令，带有日志输出
 
[postgres@db1 etc]$ pgpool -nd >/tmp/pgpool.log 2>&1 &
[postgres@db1 etc]$ netstat -ntlp
 (Not all processes could be identified, non-owned process info
  will not be shown, you would have to be root to see it all.)
 Active Internet connections (only servers)
 Proto Recv-Q Send-Q Local Address              Foreign Address            State      PID/Program name   
 tcp        0      0 0.0.0.0:22                  0.0.0.0:*                  LISTEN      -                   
 tcp        0      0 127.0.0.1:25                0.0.0.0:*                  LISTEN      -                   
 tcp        0      0 0.0.0.0:9898                0.0.0.0:*                  LISTEN      16664/pgpool       
 tcp        0      0 0.0.0.0:9999                0.0.0.0:*                  LISTEN      16664/pgpool       
 tcp        0      0 :::22                      :::*                        LISTEN      -                   
 tcp        0      0 ::1:25                      :::*                        LISTEN      -                   
 tcp        0      0 :::9999                    :::*                        LISTEN      16664/pgpool

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[postgres@db1 etc]$ psql -U postgres -h db1 -p 9999
 psql (9.2.1)
 Type "help" for help.
 postgres=# show pool_nodes;
 node_id | hostname | port | status | lb_weight |  role   
---------+----------+------+--------+-----------+---------
 0      | db1      | 5432 | 2      | 0.500000  | primary
 1      | db2      | 5432 | 2      | 0.500000  | standby
(2 rows)
 postgres=# create database db0;
 CREATE DATABASE

2：启动
3：死啦

测试可以登录，可以读写

四、故障切换

首先停止DBmaster
[postgres@db1 etc]$ pg_ctl -m fast stop

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[postgres@db1 etc]$ psql -U postgres -h db1 -p 9999
 postgres=# show pool_nodes;
 node_id | hostname | port | status | lb_weight |  role   
---------+----------+------+--------+-----------+---------
 0      | db1      | 5432 | 3      | 0.500000  | standby
 1      | db2      | 5432 | 2      | 0.500000  | primary
(2 rows)

此时DBslave显示的日志信息

[postgres@db2 data]$ FATAL:  replication terminated by primary server
LOG:  record with zero length at 0/10000FE0
LOG:  trigger file found: /tmp/trigger_file
LOG:  redo done at 0/10000F80
LOG:  last completed transaction was at log time 2015-06-17 11:05:44.379009+08
LOG:  selected new timeline ID: 2
LOG:  archive recovery complete
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started

DBmaster 已经死啦，状态切换为standby；DBslave切换为primary；测试可读写
日志提示，发现 trigger_file文件，进行切换
DBslave 切换为 主服务器
recover.conf自动更改为recover.done

[postgres@db2 data]$ ll /opt/data/recovery.done
recovery.done

故障切换成功

五、恢复DBmaster

1、同步DBmaster至DBslave

pg_basebackup -D $PGDATA -Fp -Xs -v  -h db1 -p 5432 -U postgres

2、修改配置文件

listen_addresses = '*'
port = 5432
hot_standby = on

3、修改recover文件

mv recover.done  recover.conf
vim recover.conf
primary_conninfo = 'host=172.16.0.133 port=5432 user=postgres'

4、启动DBslave
5、添加node

pcp_attach_node -d 5 db1 9898 postgres postgres 0
pcp_attach_node -d 5 db1 9898 postgres postgres 1

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