一、总体架构
二、环境申请
三、配置4台主机之间的互信
四、配置repmgr
4.1、主库修改pg_hba.conf参数文件
4.2、主库修改postgresql.conf参数文件
4.3、主库创建相关用户和数据库
4.4、4个节点分别修改repmgr.conf
4.5、在主库注册主库服务
4.6、克隆备库1和备库2
4.6.1、4个节点都配~/.pgpass密码文件
4.6.2、克隆备库1
4.6.3、克隆备库2
4.6.4、注册从库服务
4.7、配置witness
4.7.1、初始化witness数据库
4.7.1.1、初始化并启动数据库
4.7.1.2、创建相关用户和数据库
4.7.2、注册为witness节点
五、检查repmgr集群
六、主从切换
6.1、switchover正常主从切换
6.1.1、把备库62变为主库
6.1.2、把新备库61切换为主库
6.2、failover切换
6.2.1、failover异常手工主从切换
6.2.2、failover异常自动主从切换
七、配置Pgpool-II做读写分离+负载均衡
7.1、安装Pgpool-II
7.2、配置pgpool.conf
7.3、在主库创建用户
7.4、启动Pgpool-II
7.5、查询
7.6、switchover故障转移后,查询读写分离
八、总结
本文最终需要实现的目标:
1、1主2从流复制
2、读写分离+负载均衡(pgpool-II)
3、主从自动切换(repmgr)
所有的节点:安装操作系统、创建PG用户目录、安装PG软件、安装repmgr
主库:只初始化主库、启动主库归档
先申请4台机器,6.66节点最后再申请,反正docker容器都是即开即用的。
-- 主库
docker rm -f lhrrepmgr64361
docker run -d --name lhrrepmgr64361 -h lhrrepmgr64361 \
--net=pg-network --ip 172.72.6.61 \
-p 64361:5432 \
-v /sys/fs/cgroup:/sys/fs/cgroup \
--privileged=true lhrbest/lhrpgall:1.0 \
/usr/sbin/init
docker network connect bridge lhrrepmgr64361
-- 从库1
docker rm -f lhrrepmgr64362
docker run -d --name lhrrepmgr64362 -h lhrrepmgr64362 \
--net=pg-network --ip 172.72.6.62 \
-p 64362:5432 \
-v /sys/fs/cgroup:/sys/fs/cgroup \
--privileged=true lhrbest/lhrpgall:1.0 \
/usr/sbin/init
docker network connect bridge lhrrepmgr64362
-- 从库2
docker rm -f lhrrepmgr64363
docker run -d --name lhrrepmgr64363 -h lhrrepmgr64363 \
--net=pg-network --ip 172.72.6.63 \
-p 64363:5432 \
-v /sys/fs/cgroup:/sys/fs/cgroup \
--privileged=true lhrbest/lhrpgall:1.0 \
/usr/sbin/init
docker network connect bridge lhrrepmgr64363
-- Witness库
docker rm -f lhrrepmgr64364
docker run -d --name lhrrepmgr64364 -h lhrrepmgr64364 \
--net=pg-network --ip 172.72.6.64 \
-p 64364:5432 \
-v /sys/fs/cgroup:/sys/fs/cgroup \
--privileged=true lhrbest/lhrpgall:1.0 \
/usr/sbin/init
docker network connect bridge lhrrepmgr64364
-- 重启4台机器
docker restart lhrrepmgr64361 lhrrepmgr64362 lhrrepmgr64363 lhrrepmgr64364
[root@docker35 ~]# docker ps | grep repmgr
31d3d31c1073 lhrbest/lhrpgall:1.0 "/usr/sbin/init" 41 hours ago Up 41 hours 5433-5435/tcp, 0.0.0.0:64364->5432/tcp lhrrepmgr64364
572d4ea2c072 lhrbest/lhrpgall:1.0 "/usr/sbin/init" 41 hours ago Up 41 hours 5433-5435/tcp, 0.0.0.0:64363->5432/tcp lhrrepmgr64363
6ded416b2016 lhrbest/lhrpgall:1.0 "/usr/sbin/init" 41 hours ago Up 41 hours 5433-5435/tcp, 0.0.0.0:64362->5432/tcp lhrrepmgr64362
fa38b58b8f3d lhrbest/lhrpgall:1.0 "/usr/sbin/init" 41 hours ago Up 41 hours 5433-5435/tcp, 0.0.0.0:64361->5432/tcp lhrrepmgr64361
[root@docker35 ~]#
👉 注意: 1、镜像lhrbest/lhrpgall:1.0中,申请的4台主机均已安装好PG 13和repmgr软件 2、PG安装方式为编译安装,数据库已初始化完成,用户为pg13 3、该镜像里已安装了PG13、PG12、PG11、PG10和PG9.6这几个版本,均为编译安装,本文使用PG13来操作
-- 只在主库61节点上,以root用户执行:
chmod +x sshUserSetup.sh
./sshUserSetup.sh -user pg13 -hosts "172.72.6.61 172.72.6.62 172.72.6.63 172.72.6.64" -advanced exverify -confirm
-- 在每台主机修改权限,否则报错:Bad owner or permissions on /home/pg13/.ssh/config
chmod 600 /home/pg13/.ssh/config
依次输入:yes,回车和密码即可。
脚本下载:https://share.weiyun.com/57HUxNi
验证:
ssh pg13@lhrrepmgr64361 date
ssh pg13@lhrrepmgr64362 date
ssh pg13@lhrrepmgr64363 date
ssh pg13@lhrrepmgr64364 date
第二次执行时不再提示输入yes,并且可以成功执行命令,则表示SSH对等性配置成功。
执行过程:
[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64362 date
Tue Apr 27 17:15:04 CST 2021
[root@lhrrepmgr64361 /]#
[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64363 date
Tue Apr 27 17:15:08 CST 2021
[root@lhrrepmgr64361 /]#
[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64364 date
Tue Apr 27 17:15:13 CST 2021
[pg13@lhrrepmgr64361 /]#
-- 进入主库
docker exec -it lhrrepmgr64361 bash
su - pg13
cat >> /pg13/pgdata/pg_hba.conf <<"EOF"
local repmgr repmgr md5
host repmgr repmgr 127.0.0.1/32 md5
host repmgr repmgr 172.72.6.0/24 md5
local replication repmgr md5
host replication repmgr 127.0.0.1/32 md5
host replication repmgr 172.72.6.0/24 md5
EOF
-- 修改参数
cat >> /pg13/pgdata/postgresql.conf <<"EOF"
# 归档参数
wal_level='replica'
archive_mode='on'
archive_command='test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f'
restore_command='cp /pg13/archive/%f %p'
# 主从流复制
hot_standby=on
max_wal_senders=10
wal_sender_timeout=60s
wal_keep_size=16MB
# 主从切换参数,启用PG数据库的复制槽,PG12不需要"use_replication_slots=true"这个参数了。
max_replication_slots=10
wal_log_hints=on
# 自动切换
shared_preload_libraries ='repmgr'
EOF
-- 重启
pg_ctl start
-- 查询
psql -U postgres -h 192.168.66.35 -p 64361
select * from pg_settings where name in ('wal_level','archive_mode','archive_command');
-- 切换归档
select pg_switch_wal();
-- 创建相关用户和数据库
su - pg13
createuser -s repmgr
createdb repmgr -O repmgr
psql -h 127.0.0.1 -c "alter user repmgr with password 'lhr';"
psql -h 127.0.0.1 -c "alter user repmgr set search_path to repmgr, \"\$user\",public;"
结果:
[root@lhrrepmgr64361 /]# systemctl start pg13
[root@lhrrepmgr64361 /]# systemctl status pg13
● pg13.service - PostgreSQL database server
Loaded: loaded (/etc/systemd/system/pg13.service; disabled; vendor preset: disabled)
Active: active (running) since Tue 2021-04-27 16:25:24 CST; 6s ago
Docs: man:postgres(1)
Process: 769 ExecStart=/pg13/pg13/bin/pg_ctl start -D ${PGDATA} -s -o -p ${PGPORT} -w -t 300 (code=exited, status=0/SUCCESS)
Main PID: 771 (postgres)
CGroup: /docker/a777ef12d5ff83a9d47be51a98531bd45b42d2b008f7a25f894f3244ce9cc0d4/system.slice/pg13.service
├─771 /pg13/pg13/bin/postgres -D /pg13/pgdata -p 5432
├─772 postgres: logger
├─774 postgres: checkpointer
├─775 postgres: background writer
├─776 postgres: walwriter
├─777 postgres: autovacuum launcher
├─778 postgres: stats collector
└─779 postgres: logical replication launcher
Apr 27 16:25:23 lhrrepmgr64361 systemd[1]: Starting PostgreSQL database server...
Apr 27 16:25:24 lhrrepmgr64361 pg_ctl[769]: 2021-04-27 16:25:24.024 CST [771] LOG: redirecting log output to logging collector process
Apr 27 16:25:24 lhrrepmgr64361 pg_ctl[769]: 2021-04-27 16:25:24.024 CST [771] HINT: Future log output will appear in directory "pg_log".
Apr 27 16:25:24 lhrrepmgr64361 systemd[1]: Started PostgreSQL database server.
[root@lhrrepmgr64361 /]# su - pg13
Last login: Tue Apr 27 16:24:50 CST 2021 on pts/0
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ createuser -s repmgr
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ createdb repmgr -O repmgr
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ psql -h 127.0.0.1 -c "alter user repmgr with password 'lhr'"
ALTER ROLE
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ psql -h 127.0.0.1 -c "alter user repmgr set search_path to repmgr, \"\$user\",public";
ALTER ROLE
C:\Users\lhrxxt>psql -U postgres -h 192.168.66.35 -p 64361
Password for user postgres:
psql (13.2)
Type "help" for help.
postgres=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------+-----------
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
repmgr | Superuser, Create role, Create DB | {}
postgres=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+------------+------------+-----------------------
postgres | postgres | UTF8 | en_US.utf8 | en_US.utf8 |
repmgr | repmgr | UTF8 | en_US.utf8 | en_US.utf8 |
template0 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.utf8 | en_US.utf8 | =c/postgres +
| | | | | postgres=CTc/postgres
(4 rows)
-- 以pg13用户修改
su - pg13
-- 主库
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=1
node_name=lhrrepmgr64361
conninfo='host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF
-- 从库1
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=2
node_name=lhrrepmgr64362
conninfo='host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF
-- 从库2
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=3
node_name=lhrrepmgr64363
conninfo='host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF
-- witness节点
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=4
node_name=lhrrepmgr64364
conninfo='host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF
-- 测试
psql 'host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
-- 注册服务
repmgr -f /pg13/pg13/repmgr.conf primary register
-- 查询
repmgr -f /pg13/pg13/repmgr.conf cluster show
psql -U repmgr -h 192.168.66.35 -p 64361 -d repmgr
执行过程:
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf primary register
INFO: connecting to primary database...
NOTICE: attempting to install extension "repmgr"
NOTICE: "repmgr" extension successfully installed
NOTICE: primary node record (ID: 1) registered
[pg13@lhrrepmgr64361 pg13]$
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 1 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
C:\Users\lhrxxt>psql -U repmgr -h 192.168.66.35 -p 64361 -d repmgr
Password for user repmgr:
psql (13.2)
Type "help" for help.
repmgr=# select * from repmgr.nodes;
node_id | upstream_node_id | active | node_name | type | location | priority | conninfo | repluser | slot_name | config_file
---------+------------------+--------+----------------+---------+----------+----------+---------------------------------------------------------------------------+----------+-----------+------------------------
1 | | t | lhrrepmgr64361 | primary | default | 100 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr | | /pg13/pg13/repmgr.conf
(1 row)
su - pg13
echo "*:*:*:repmgr:lhr" > ~/.pgpass
chmod 0600 ~/.pgpass
-- 测试,若不需要密码,那就证明配置正确
psql 'host=172.72.6.61 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.62 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.64 user=repmgr dbname=repmgr connect_timeout=2'
-- 其中--dry-run表示不真实执行克隆过程,只是检查是否有问题
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force --dry-run
-- 执行克隆命令,其实还是调用pg_basebackup
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force
-- 启动
pg_ctl -D /pg13/pgdata start
-- 查询
psql
select * from pg_stat_wal_receiver;
执行过程:
[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force --dry-run
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
INFO: "repmgr" extension is installed in database "repmgr"
WARNING: target data directory appears to be a PostgreSQL data directory
DETAIL: target data directory is "/pg13/pgdata"
HINT: use -F/--force to overwrite the existing data directory
INFO: replication slot usage not requested; no replication slot will be set up for this standby
INFO: parameter "max_wal_senders" set to 10
NOTICE: checking for available walsenders on the source node (2 required)
INFO: sufficient walsenders available on the source node
DETAIL: 2 required, 10 available
NOTICE: checking replication connections can be made to the source server (2 required)
INFO: required number of replication connections could be made to the source server
DETAIL: 2 replication connections required
WARNING: data checksums are not enabled and "wal_log_hints" is "off"
DETAIL: pg_rewind requires "wal_log_hints" to be enabled
NOTICE: standby will attach to upstream node 1
HINT: consider using the -c/--fast-checkpoint option
INFO: all prerequisites for "standby clone" are met
[pg13@lhrrepmgr64362 ~]$ repmgrrepmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone^C
[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
ERROR: target data directory appears to be a PostgreSQL data directory
DETAIL: target data directory is "/pg13/pgdata"
HINT: use -F/--force to overwrite the existing data directory
[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
INFO: replication slot usage not requested; no replication slot will be set up for this standby
NOTICE: checking for available walsenders on the source node (2 required)
NOTICE: checking replication connections can be made to the source server (2 required)
WARNING: data checksums are not enabled and "wal_log_hints" is "off"
DETAIL: pg_rewind requires "wal_log_hints" to be enabled
WARNING: directory "/pg13/pgdata" exists but is not empty
NOTICE: -F/--force provided - deleting existing data directory "/pg13/pgdata"
NOTICE: starting backup (using pg_basebackup)...
HINT: this may take some time; consider using the -c/--fast-checkpoint option
INFO: executing:
/pg13/pg13/bin/pg_basebackup -l "repmgr base backup" -D /pg13/pgdata -h 172.72.6.61 -p 5432 -U repmgr -X stream
Password:
WARNING: skipping special file "./.s.PGSQL.5432"
WARNING: skipping special file "./.s.PGSQL.5432"
NOTICE: standby clone (using pg_basebackup) complete
NOTICE: you can now start your PostgreSQL server
HINT: for example: pg_ctl -D /pg13/pgdata start
HINT: after starting the server, you need to register this standby with "repmgr standby register"
[pg13@lhrrepmgr64362 ~]$ pg_ctl -D /pg13/pgdata start
waiting for server to start....2021-04-27 19:14:08.750 CST [9298] LOG: redirecting log output to logging collector process
2021-04-27 19:14:08.750 CST [9298] HINT: Future log output will appear in directory "pg_log".
done
server started
[pg13@lhrrepmgr64362 ~]$ psql
psql (13.2)
Type "help" for help.
postgres=# select * from pg_stat_wal_receiver;
pid | status | receive_start_lsn | receive_start_tli | written_lsn | flushed_lsn | received_tli | last_msg_send_time | last_msg_receipt_time | latest_end_lsn | latest_end_time | slot_name | sender_host | sender_port | conninfo
------+-----------+-------------------+-------------------+-------------+-------------+--------------+-------------------------------+-------------------------------+----------------+-------------------------------+-----------+-------------+-------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
9304 | streaming | 0/3000000 | 1 | 0/30001F0 | 0/30001F0 | 1 | 2021-04-27 19:15:08.862599+08 | 2021-04-27 19:15:08.862719+08 | 0/30001F0 | 2021-04-27 19:14:08.830865+08 | | 172.72.6.61 | 5432 | user=repmgr password=******** channel_binding=disable connect_timeout=2 dbname=replication host=172.72.6.61 port=5432 application_name=lhrrepmgr64362 fallback_application_name=walreceiver sslmode=disable sslcompression=0 ssl_min_protocol_version=TLSv1.2 gssencmode=disable krbsrvname=postgres target_session_attrs=any
(1 row)
信息“NOTICE: standby clone (using pg_basebackup) complete”表示测试完成。
-- 其中--dry-run表示不真实执行克隆过程,只是检查是否有问题
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force --dry-run
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force
-- 启动
pg_ctl -D /pg13/pgdata start
-- 查询
psql
select * from pg_stat_wal_receiver;
-- 分别在2个从库注册
repmgr -f /pg13/pg13/repmgr.conf standby register --force
repmgr -f /pg13/pg13/repmgr.conf cluster show
执行过程:
-- 从库2
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby register
INFO: connecting to local node "lhrrepmgr64362" (ID: 2)
INFO: connecting to primary database
WARNING: --upstream-node-id not supplied, assuming upstream node is primary (node ID 1)
INFO: standby registration complete
NOTICE: standby node "lhrrepmgr64362" (ID: 2) successfully registered
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 1 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 1 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
-- 从库3
[pg13@lhrrepmgr64363 pgdata]$ repmgr -f /pg13/pg13/repmgr.conf standby register
INFO: connecting to local node "lhrrepmgr64363" (ID: 3)
repmgr -f /pg13/pg13/repmgr.conf cluster showINFO: connecting to primary database
WARNING: --upstream-node-id not supplied, assuming upstream node is primary (node ID 1)
INFO: standby registration complete
NOTICE: standby node "lhrrepmgr64363" (ID: 3) successfully registered
[pg13@lhrrepmgr64363 pgdata]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 1 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 1 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 1 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
witness节点不能克隆,只能初始化数据库。
-- 需要重新初始化环境
rm -rf /pg13/pgdata
/pg13/pg13/bin/initdb -D /pg13/pgdata -E UTF8 --locale=en_US.utf8 -U postgres
-- 修改参数postgresql.conf
cat >> /pg13/pgdata/postgresql.conf <<"EOF"
listen_addresses = '*'
port=5432
unix_socket_directories='/pg13/pgdata'
logging_collector = on
log_directory = 'pg_log'
log_filename = 'postgresql-%a.log'
log_truncate_on_rotation = on
# 归档参数
wal_level='replica'
archive_mode='on'
archive_command='test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f'
restore_command='cp /pg13/archive/%f %p'
# 主从流复制
hot_standby=on
max_wal_senders=10
wal_sender_timeout=60s
wal_keep_size=16MB
# 主从切换参数,启用PG数据库的复制槽,PG12不需要"use_replication_slots=true"这个参数了。
max_replication_slots=10
wal_log_hints=on
# 自动切换
shared_preload_libraries ='repmgr'
EOF
-- 修改参数pg_hba.conf
cat >> /pg13/pgdata/pg_hba.conf <<"EOF"
# TYPE DATABASE USER ADDRESS METHOD
local all all trust
host all all 127.0.0.1/32 trust
host all all 0.0.0.0/0 md5
host replication all 0.0.0.0/0 md5
local repmgr repmgr md5
host repmgr repmgr 127.0.0.1/32 md5
host repmgr repmgr 172.72.6.0/24 md5
local replication repmgr md5
host replication repmgr 127.0.0.1/32 md5
host replication repmgr 172.72.6.0/24 md5
EOF
-- 启动数据库
/pg13/pg13/bin/pg_ctl -D /pg13/pgdata -l logfile start
su - pg13
createuser -s repmgr
createdb repmgr -O repmgr
psql -h 127.0.0.1 -c "alter user repmgr with password 'lhr';"
psql -h 127.0.0.1 -c "alter user repmgr set search_path to repmgr, \"\$user\",public;"
repmgr -f /pg13/pg13/repmgr.conf witness register -h 172.72.6.61 -U repmgr -d repmgr --force
repmgr -f /pg13/pg13/repmgr.conf cluster show
执行过程:
[pg13@lhrrepmgr64364 ~]$ repmgr -f /pg13/pg13/repmgr.conf witness register -h 172.72.6.61 -U repmgr -d repmgr --force
INFO: connecting to witness node "lhrrepmgr64364" (ID: 4)
INFO: connecting to primary node
NOTICE: attempting to install extension "repmgr"
NOTICE: "repmgr" extension successfully installed
INFO: witness registration complete
NOTICE: witness node "lhrrepmgr64364" (ID: 4) successfully registered
-- 所有节点查询都可以获取如下的结果
[pg13@lhrrepmgr64364 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 1 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 1 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 1 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
repmgr=# select * from pg_stat_replication;
pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | backend_xmin | state | sent_lsn | write_lsn | flush_lsn | replay_lsn | write_lag | flush_lag | replay_lag | sync_priority | sync_state | reply_time
------+----------+---------+------------------+-------------+-----------------+-------------+-------------------------------+--------------+-----------+------------+------------+------------+------------+-----------+-----------+------------+---------------+------------+-------------------------------
7270 | 16385 | repmgr | lhrrepmgr64362 | 172.72.6.62 | | 54710 | 2021-04-28 19:07:18.248872+08 | | streaming | 0/7DF703C0 | 0/7DF703C0 | 0/7DF703C0 | 0/7DF703C0 | | | | 0 | async | 2021-04-29 12:06:07.924676+08
7276 | 16385 | repmgr | lhrrepmgr64363 | 172.72.6.63 | | 54888 | 2021-04-28 19:07:18.678135+08 | | streaming | 0/7DF703C0 | 0/7DF703C0 | 0/7DF703C0 | 0/7DF703C0 | | | | 0 | async | 2021-04-29 12:06:07.956466+08
(2 rows)
repmgr -f /pg13/pg13/repmgr.conf cluster matrix
repmgr -f /pg13/pg13/repmgr.conf cluster crosscheck
repmgr -f /pg13/pg13/repmgr.conf node status
repmgr -f /pg13/pg13/repmgr.conf node check
一些结果:
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster matrix
INFO: connecting to database
Name | ID | 1 | 2 | 3 | 4
----------------+----+---+---+---+---
lhrrepmgr64361 | 1 | * | * | * | *
lhrrepmgr64362 | 2 | * | * | * | *
lhrrepmgr64363 | 3 | * | * | * | *
lhrrepmgr64364 | 4 | * | * | * | *
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf node status
Node "lhrrepmgr64361":
PostgreSQL version: 13.2
Total data size: 37 MB
Conninfo: host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
Role: primary
WAL archiving: enabled
Archive command: test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f
WALs pending archiving: 0 pending files
Replication connections: 2 (of maximal 10)
Replication slots: 0 physical (of maximal 10; 0 missing)
Replication lag: n/a
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf node check
Node "lhrrepmgr64361":
Server role: OK (node is primary)
Replication lag: OK (N/A - node is primary)
WAL archiving: OK (0 pending archive ready files)
Upstream connection: OK (N/A - node is primary)
Downstream servers: OK (2 of 2 downstream nodes attached)
Replication slots: OK (node has no physical replication slots)
Missing physical replication slots: OK (node has no missing physical replication slots)
Configured data directory: OK (configured "data_directory" is "/pg13/pgdata")
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf node status
Node "lhrrepmgr64362":
PostgreSQL version: 13.2
Total data size: 37 MB
Conninfo: host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
Role: standby
WAL archiving: disabled (on standbys "archive_mode" must be set to "always" to be effective)
Archive command: test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f
WALs pending archiving: 0 pending files
Replication connections: 0 (of maximal 10)
Replication slots: 0 physical (of maximal 10; 0 missing)
Upstream node: lhrrepmgr64361 (ID: 1)
Replication lag: 0 seconds
Last received LSN: 0/8001480
Last replayed LSN: 0/8001480
[pg13@lhrrepmgr64364 ~]$ repmgr -f /pg13/pg13/repmgr.conf node status
Node "lhrrepmgr64364":
PostgreSQL version: 13.2
Total data size: 29 MB
Conninfo: host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
Role: witness
WAL archiving: enabled
Archive command: test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f
WALs pending archiving: 0 pending files
Replication connections: 0 (of maximal 10)
Replication slots: 0 physical (of maximal 10; 0 missing)
Replication lag: n/a
switchover切换即主变备,备变主。
官网:https://repmgr.org/docs/current/repmgr-standby-switchover.html
在62上操作:
repmgr -f /pg13/pg13/repmgr.conf cluster show
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --dry-run --force-rewind
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
repmgr -f /pg13/pg13/repmgr.conf cluster show
-- 可以debug打印详细的切换过程
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind --log-level DEBUG --verbose
--siblings-follow 表示所有的从库同步源自动改成最新的主库节点 --force-rewind 如果repmgr检测到需要执行pg_rewind(同步)的时候,在执行pg_rewind之前,在新主节点执行checkpoint
执行过程:
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 3 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 3 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 3 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64362 ~]$
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --dry-run --force-rewind
NOTICE: checking switchover on node "lhrrepmgr64362" (ID: 2) in --dry-run mode
INFO: prerequisites for using pg_rewind are met
INFO: SSH connection to host "172.72.6.61" succeeded
INFO: able to execute "repmgr" on remote host "172.72.6.61"
INFO: all sibling nodes are reachable via SSH
INFO: 3 walsenders required, 10 available
INFO: demotion candidate is able to make replication connection to promotion candidate
INFO: 0 pending archive files
INFO: replication lag on this standby is 0 seconds
NOTICE: local node "lhrrepmgr64362" (ID: 2) would be promoted to primary; current primary "lhrrepmgr64361" (ID: 1) would be demoted to standby
INFO: following shutdown command would be run on node "lhrrepmgr64361":
"/pg13/pg13/bin/pg_ctl -D '/pg13/pgdata' -W -m fast stop"
INFO: parameter "shutdown_check_timeout" is set to 60 seconds
INFO: prerequisites for executing STANDBY SWITCHOVER are met
[pg13@lhrrepmgr64362 ~]$
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
NOTICE: executing switchover on node "lhrrepmgr64362" (ID: 2)
NOTICE: local node "lhrrepmgr64362" (ID: 2) will be promoted to primary; current primary "lhrrepmgr64361" (ID: 1) will be demoted to standby
NOTICE: stopping current primary node "lhrrepmgr64361" (ID: 1)
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64361" (ID: 1)
DETAIL: executing server command "/pg13/pg13/bin/pg_ctl -D '/pg13/pgdata' -W -m fast stop"
INFO: checking for primary shutdown; 1 of 60 attempts ("shutdown_check_timeout")
INFO: checking for primary shutdown; 2 of 60 attempts ("shutdown_check_timeout")
NOTICE: current primary has been cleanly shut down at location 0/9000028
NOTICE: promoting standby to primary
DETAIL: promoting server "lhrrepmgr64362" (ID: 2) using pg_promote()
NOTICE: waiting up to 60 seconds (parameter "promote_check_timeout") for promotion to complete
NOTICE: STANDBY PROMOTE successful
DETAIL: server "lhrrepmgr64362" (ID: 2) was successfully promoted to primary
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64362" (ID: 2)
ERROR: unable to execute CHECKPOINT
INFO: local node 1 can attach to rejoin target node 2
DETAIL: local node's recovery point: 0/9000028; rejoin target node's fork point: 0/90000A0
NOTICE: setting node 1 upstream to node 2
WARNING: unable to ping "host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
DETAIL: PQping() returned "PQPING_NO_RESPONSE"
NOTICE: starting server using "/pg13/pg13/bin/pg_ctl -w -D '/pg13/pgdata' start"
NOTICE: NODE REJOIN successful
DETAIL: node 1 is now attached to node 2
NOTICE: node "lhrrepmgr64362" (ID: 2) promoted to primary, node "lhrrepmgr64361" (ID: 1) demoted to standby
NOTICE: executing STANDBY FOLLOW on 2 of 2 siblings
INFO: STANDBY FOLLOW successfully executed on all reachable sibling nodes
NOTICE: switchover was successful
DETAIL: node "lhrrepmgr64362" is now primary and node "lhrrepmgr64361" is attached as standby
NOTICE: STANDBY SWITCHOVER has completed successfully
[pg13@lhrrepmgr64362 ~]$
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | standby | running | lhrrepmgr64362 | default | 100 | 3 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | primary | * running | | default | 100 | 4 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64362 | default | 100 | 3 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64362 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
C:\Users\lhrxxt>psql -U repmgr -h192.168.66.35 -p64361 -d repmgr
Password for user repmgr:
psql (13.2)
Type "help" for help.
repmgr=# select * from nodes;
node_id | upstream_node_id | active | node_name | type | location | priority | conninfo | repluser | slot_name | config_file
---------+------------------+--------+----------------+---------+----------+----------+---------------------------------------------------------------------------+----------+-----------+------------------------
2 | | t | lhrrepmgr64362 | primary | default | 100 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr | | /pg13/pg13/repmgr.conf
1 | 2 | t | lhrrepmgr64361 | standby | default | 100 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr | | /pg13/pg13/repmgr.conf
3 | 2 | t | lhrrepmgr64363 | standby | default | 100 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr | | /pg13/pg13/repmgr.conf
4 | 2 | t | lhrrepmgr64364 | witness | default | 0 | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr | | /pg13/pg13/repmgr.conf
(4 rows)
可以看到,主库变为lhrrepmgr64362,而lhrrepmgr64361变为了从库。
-- 在61上做操作
repmgr -f /pg13/pg13/repmgr.conf cluster show
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --dry-run --force-rewind
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
-- 可以debug打印详细的切换过程
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind --log-level DEBUG --verbose
执行过程:
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | standby | running | lhrrepmgr64362 | default | 100 | 4 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | primary | * running | | default | 100 | 4 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64362 | default | 100 | 4 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64362 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --dry-run --force-rewind
NOTICE: checking switchover on node "lhrrepmgr64361" (ID: 1) in --dry-run mode
INFO: prerequisites for using pg_rewind are met
INFO: SSH connection to host "172.72.6.62" succeeded
INFO: able to execute "repmgr" on remote host "172.72.6.62"
INFO: all sibling nodes are reachable via SSH
INFO: 3 walsenders required, 10 available
INFO: demotion candidate is able to make replication connection to promotion candidate
INFO: 0 pending archive files
INFO: replication lag on this standby is 0 seconds
NOTICE: local node "lhrrepmgr64361" (ID: 1) would be promoted to primary; current primary "lhrrepmgr64362" (ID: 2) would be demoted to standby
INFO: following shutdown command would be run on node "lhrrepmgr64362":
"/pg13/pg13/bin/pg_ctl -D '/pg13/pgdata' -W -m fast stop"
INFO: parameter "shutdown_check_timeout" is set to 60 seconds
INFO: prerequisites for executing STANDBY SWITCHOVER are met
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
NOTICE: executing switchover on node "lhrrepmgr64361" (ID: 1)
NOTICE: local node "lhrrepmgr64361" (ID: 1) will be promoted to primary; current primary "lhrrepmgr64362" (ID: 2) will be demoted to standby
NOTICE: stopping current primary node "lhrrepmgr64362" (ID: 2)
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64362" (ID: 2)
DETAIL: executing server command "/pg13/pg13/bin/pg_ctl -D '/pg13/pgdata' -W -m fast stop"
INFO: checking for primary shutdown; 1 of 60 attempts ("shutdown_check_timeout")
INFO: checking for primary shutdown; 2 of 60 attempts ("shutdown_check_timeout")
NOTICE: current primary has been cleanly shut down at location 0/A000028
NOTICE: promoting standby to primary
DETAIL: promoting server "lhrrepmgr64361" (ID: 1) using pg_promote()
NOTICE: waiting up to 60 seconds (parameter "promote_check_timeout") for promotion to complete
NOTICE: STANDBY PROMOTE successful
DETAIL: server "lhrrepmgr64361" (ID: 1) was successfully promoted to primary
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64361" (ID: 1)
ERROR: unable to execute CHECKPOINT
INFO: local node 2 can attach to rejoin target node 1
DETAIL: local node's recovery point: 0/A000028; rejoin target node's fork point: 0/A0000A0
NOTICE: setting node 2's upstream to node 1
WARNING: unable to ping "host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
DETAIL: PQping() returned "PQPING_NO_RESPONSE"
NOTICE: starting server using "/pg13/pg13/bin/pg_ctl -w -D '/pg13/pgdata' start"
NOTICE: NODE REJOIN successful
DETAIL: node 2 is now attached to node 1
NOTICE: node "lhrrepmgr64361" (ID: 1) promoted to primary, node "lhrrepmgr64362" (ID: 2) demoted to standby
NOTICE: executing STANDBY FOLLOW on 2 of 2 siblings
INFO: STANDBY FOLLOW successfully executed on all reachable sibling nodes
NOTICE: switchover was successful
DETAIL: node "lhrrepmgr64361" is now primary and node "lhrrepmgr64362" is attached as standby
NOTICE: STANDBY SWITCHOVER has completed successfully
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 5 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 4 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 4 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
主库出现故障,然后直接将从库提升为主库:
-- 主库61宕机
pg_ctl -m fast stop
-- 从库63提升为主库
repmgr -f /pg13/pg13/repmgr.conf cluster show
repmgr -f /pg13/pg13/repmgr.conf --siblings-follow standby promote
repmgr -f /pg13/pg13/repmgr.conf cluster show
-- 等原主库61修复之后,由于新提升的主库63数据已经很新了,所以只能把61作为备库来运行
pg_ctl stop
repmgr -f /pg13/pg13/repmgr.conf node rejoin -d 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2' --force-rewind --dry-run --verbose
repmgr -f /pg13/pg13/repmgr.conf node rejoin -d 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2' --force-rewind --verbose
执行过程:
-- 主库61宕机
[pg13@lhrrepmgr64361 ~]$ pg_ctl -m fast stop
waiting for server to shut down.... done
server stopped
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ERROR: connection to database failed
DETAIL:
could not connect to server: Connection refused
Is the server running on host "172.72.6.61" and accepting
TCP/IP connections on port 5432?
DETAIL: attempted to connect using:
user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr options=-csearch_path=
-- 从库63提升为主库
[pg13@lhrrepmgr64363 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+---------------+------------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | ? unreachable | ? | default | 100 | | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | ? lhrrepmgr64361 | default | 100 | 5 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | ? lhrrepmgr64361 | default | 100 | 5 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | ? lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
WARNING: following issues were detected
- unable to connect to node "lhrrepmgr64361" (ID: 1)
- node "lhrrepmgr64361" (ID: 1) is registered as an active primary but is unreachable
- unable to connect to node "lhrrepmgr64362" (ID: 2)'s upstream node "lhrrepmgr64361" (ID: 1)
- unable to determine if node "lhrrepmgr64362" (ID: 2) is attached to its upstream node "lhrrepmgr64361" (ID: 1)
- unable to connect to node "lhrrepmgr64363" (ID: 3)'s upstream node "lhrrepmgr64361" (ID: 1)
- unable to determine if node "lhrrepmgr64363" (ID: 3) is attached to its upstream node "lhrrepmgr64361" (ID: 1)
- unable to connect to node "lhrrepmgr64364" (ID: 4)'s upstream node "lhrrepmgr64361" (ID: 1)'
HINT: execute with --verbose option to see connection error messages
[pg13@lhrrepmgr64363 ~]$ repmgr -f /pg13/pg13/repmgr.conf --siblings-follow standby promote
NOTICE: promoting standby to primary
DETAIL: promoting server "lhrrepmgr64363" (ID: 3) using pg_promote()
NOTICE: waiting up to 60 seconds (parameter "promote_check_timeout") for promotion to complete
NOTICE: STANDBY PROMOTE successful
DETAIL: server "lhrrepmgr64363" (ID: 3) was successfully promoted to primary
NOTICE: executing STANDBY FOLLOW on 2 of 2 siblings
INFO: STANDBY FOLLOW successfully executed on all reachable sibling nodes
[pg13@lhrrepmgr64363 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | - failed | ? | default | 100 | | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64363 | default | 100 | 5 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | primary | * running | | default | 100 | 6 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64363 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
WARNING: following issues were detected
- unable to connect to node "lhrrepmgr64361" (ID: 1)
HINT: execute with --verbose option to see connection error messages
修复好61后,再启动61数据库,作为63的备库:
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf node rejoin -d 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2' --force-rewind --verbose
NOTICE: using provided configuration file "/pg13/pg13/repmgr.conf"
NOTICE: pg_rewind execution required for this node to attach to rejoin target node 3
DETAIL: rejoin target server timeline 6 forked off current database system timeline 5 before current recovery point 1/1C000028
INFO: prerequisites for using pg_rewind are met
INFO: 0 files copied to "/tmp/repmgr-config-archive-lhrrepmgr64361"
NOTICE: executing pg_rewind
DETAIL: pg_rewind command is "/pg13/pg13/bin/pg_rewind -D '/pg13/pgdata' --source-server='host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'"
ERROR: pg_rewind execution failed
DETAIL: pg_rewind: servers diverged at WAL location 1/190000A0 on timeline 5
pg_rewind: rewinding from last common checkpoint at 1/19000028 on timeline 5
pg_rewind: error: could not open file "/pg13/pgdata/pg_wal/00000005000000010000001A": No such file or directory
pg_rewind: fatal: could not read WAL record at 1/1A000000
[pg13@lhrrepmgr64361 pg13]$ cp ./archive/00000005000000010000001A /pg13/pgdata/pg_wal/00000005000000010000001A
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf node rejoin -d 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2' --force-rewind --verbose
NOTICE: using provided configuration file "/pg13/pg13/repmgr.conf"
NOTICE: pg_rewind execution required for this node to attach to rejoin target node 3
DETAIL: rejoin target server timeline 6 forked off current database system timeline 5 before current recovery point 1/1C000028
INFO: prerequisites for using pg_rewind are met
INFO: 0 files copied to "/tmp/repmgr-config-archive-lhrrepmgr64361"
NOTICE: executing pg_rewind
DETAIL: pg_rewind command is "/pg13/pg13/bin/pg_rewind -D '/pg13/pgdata' --source-server='host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'"
NOTICE: 0 files copied to /pg13/pgdata
INFO: directory "/tmp/repmgr-config-archive-lhrrepmgr64361" deleted
NOTICE: setting node 1's upstream to node 3'
WARNING: unable to ping "host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
DETAIL: PQping() returned "PQPING_NO_RESPONSE"
NOTICE: starting server using "/pg13/pg13/bin/pg_ctl -w -D '/pg13/pgdata' start"
INFO: node "lhrrepmgr64361" (ID: 1) is pingable
INFO: node "lhrrepmgr64361" (ID: 1) has attached to its upstream node
NOTICE: NODE REJOIN successful
DETAIL: node 1 is now attached to node 3
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | standby | running | lhrrepmgr64363 | default | 100 | 5 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64363 | default | 100 | 6 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | primary | * running | | default | 100 | 6 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64363 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
生产建议配置自动failover切换,要配置自动failover,则需要做以下事情,在所有节点均配置:
1、在所有节点都配置:echo "shared_preload_libraries='repmgr' " >>/pg13/pgdata/postgresq.conf
,配置后重启PG。该步骤我之前已配置过。
2、在所有节点都配置文件/pg13/pg13/repmgr.conf
,增加内容包括:
cat >> /pg13/pg13/repmgr.conf << "EOF"
monitoring_history=yes
monitor_interval_secs=5
failover=automatic
reconnect_attempts=6
reconnect_interval=5
promote_command='repmgr standby promote -f /pg13/pg13/repmgr.conf --log-to-file'
follow_command='repmgr standby follow -f /pg13/pg13/repmgr.conf --log-to-file --upstream-node-id=%n'
log_level=INFO
log_status_interval=10
log_file='/pg13/pg13/repmgr.log'
EOF
cat >> /etc/logrotate.conf <<"EOF"
/pg13/pg13/repmgr.log {
missingok
compress
rotate 30
daily
dateext
create 0600 pg13 pg13
}
EOF
3、在所有节点都启动repmgrd进程
-- 启动
repmgrd -f /pg13/pg13/repmgr.conf --pid-file /tmp/repmgrd.pid --daemonize
-- 建议加到开机自动启动:/etc/rc.local
echo "repmgrd -f /pg13/pg13/repmgr.conf --pid-file /tmp/repmgrd.pid --daemonize" >> /etc/rc.local
chmod +x /etc/rc.d/rc.local
-- 停止
kill -9 `cat /tmp/repmgrd.pid`
日志:
[pg13@lhrrepmgr64363 ~]$ tailf /pg13/pg13/repmgr.log
[2021-04-29 16:34:07] [NOTICE] repmgrd (repmgrd 5.2.1) starting up
[2021-04-29 16:34:07] [INFO] connecting to database "host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
INFO: set_repmgrd_pid(): provided pidfile is /tmp/repmgrd.pid
[2021-04-29 16:34:07] [NOTICE] starting monitoring of node "lhrrepmgr64363" (ID: 3)
[2021-04-29 16:34:07] [INFO] "connection_check_type" set to "ping"
[2021-04-29 16:34:07] [INFO] monitoring connection to upstream node "lhrrepmgr64361" (ID: 1)
[2021-04-29 16:34:17] [INFO] node "lhrrepmgr64363" (ID: 3) monitoring upstream node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 16:34:17] [DETAIL] last monitoring statistics update was 5 seconds ago
[2021-04-29 16:34:27] [INFO] node "lhrrepmgr64363" (ID: 3) monitoring upstream node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 16:34:27] [DETAIL] last monitoring statistics update was 5 seconds ago
[2021-04-29 16:34:37] [INFO] node "lhrrepmgr64363" (ID: 3) monitoring upstream node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 16:34:37] [DETAIL] last monitoring statistics update was 5 seconds ago
接下来,我们宕掉主库,来观察能否发生自动切换:
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 9 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 9 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 9 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64361 ~]$ pg_ctl stop
waiting for server to shut down.... done
server stopped
观察日志输出:
[2021-04-29 17:03:08] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 17:03:19] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 17:03:29] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64361" (ID: 1) in normal state
[2021-04-29 17:03:34] [WARNING] unable to ping "host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
[2021-04-29 17:03:34] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:34] [INFO] checking state of node 1, 1 of 6 attempts
[2021-04-29 17:03:34] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:34] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:34] [INFO] sleeping 5 seconds until next reconnection attempt
[2021-04-29 17:03:39] [INFO] checking state of node 1, 2 of 6 attempts
[2021-04-29 17:03:39] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:39] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:39] [INFO] sleeping 5 seconds until next reconnection attempt
[2021-04-29 17:03:44] [INFO] checking state of node 1, 3 of 6 attempts
[2021-04-29 17:03:44] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:44] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:44] [INFO] sleeping 5 seconds until next reconnection attempt
[2021-04-29 17:03:49] [INFO] checking state of node 1, 4 of 6 attempts
[2021-04-29 17:03:49] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:49] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:49] [INFO] sleeping 5 seconds until next reconnection attempt
[2021-04-29 17:03:54] [INFO] checking state of node 1, 5 of 6 attempts
[2021-04-29 17:03:54] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:54] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:54] [INFO] sleeping 5 seconds until next reconnection attempt
[2021-04-29 17:03:59] [INFO] checking state of node 1, 6 of 6 attempts
[2021-04-29 17:03:59] [WARNING] unable to ping "user=repmgr password=lhr connect_timeout=2 dbname=repmgr host=172.72.6.61 fallback_application_name=repmgr"
[2021-04-29 17:03:59] [DETAIL] PQping() returned "PQPING_NO_RESPONSE"
[2021-04-29 17:03:59] [WARNING] unable to reconnect to node 1 after 6 attempts
[2021-04-29 17:03:59] [NOTICE] witness node "lhrrepmgr64364" (ID: 4) now following new primary node "lhrrepmgr64362" (ID: 2)
[2021-04-29 17:03:59] [INFO] resuming witness monitoring mode
[2021-04-29 17:03:59] [DETAIL] following new primary "lhrrepmgr64362" (ID: 2)
[2021-04-29 17:03:59] [INFO] witness monitoring connection to primary node "lhrrepmgr64362" (ID: 2)
[2021-04-29 17:04:09] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64362" (ID: 2) in normal state
[2021-04-29 17:04:19] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64362" (ID: 2) in normal state
[2021-04-29 17:04:29] [INFO] witness node "lhrrepmgr64364" (ID: 4) monitoring primary node "lhrrepmgr64362" (ID: 2) in normal state
可以看到,在尝试6次连接后,发生了主从切换,主库变为了lhrrepmgr64362。
查看状态:
[pg13@lhrrepmgr64362 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | - failed | ? | default | 100 | | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | primary | * running | | default | 100 | 12 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64362 | default | 100 | 12 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64362 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
WARNING: following issues were detected
- unable to connect to node "lhrrepmgr64361" (ID: 1)
HINT: execute with --verbose option to see connection error messages
接下来,等原主库61修复后,我们需要加入到现有的环境中:
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf node rejoin -d 'host=172.72.6.62 user=repmgr dbname=repmgr connect_timeout=2' --force-rewind --verbose
NOTICE: using provided configuration file "/pg13/pg13/repmgr.conf"
NOTICE: pg_rewind execution required for this node to attach to rejoin target node 2
DETAIL: rejoin target server's timeline 12 forked off current database system timeline 11 before current recovery point 1/22000028
INFO: prerequisites for using pg_rewind are met
INFO: 0 files copied to "/tmp/repmgr-config-archive-lhrrepmgr64361"
NOTICE: executing pg_rewind
DETAIL: pg_rewind command is "/pg13/pg13/bin/pg_rewind -D '/pg13/pgdata' --source-server='host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2'"
NOTICE: 0 files copied to /pg13/pgdata
INFO: directory "/tmp/repmgr-config-archive-lhrrepmgr64361" deleted
NOTICE: setting node 1's upstream to node 2
WARNING: unable to ping "host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
DETAIL: PQping() returned "PQPING_NO_RESPONSE"
NOTICE: starting server using "/pg13/pg13/bin/pg_ctl -w -D '/pg13/pgdata' start"
INFO: node "lhrrepmgr64361" (ID: 1) is pingable
INFO: node "lhrrepmgr64361" (ID: 1) has attached to its upstream node
NOTICE: NODE REJOIN successful
DETAIL: node 1 is now attached to node 2
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | standby | running | lhrrepmgr64362 | default | 100 | 11 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | primary | * running | | default | 100 | 12 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64362 | default | 100 | 12 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64362 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64361 ~]$
可以做switchover操作再切换回lhrrepmgr64361为主库的状态。
👉 详细配置过程,在《【DB宝61】PostgreSQL使用Pgpool-II实现读写分离+负载均衡》中已经讲解过了,这里简单配置即可。
-- 下载镜像
docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/lhrpgpool:4.2.2_01
-- 创建Pgpool-II的容器
docker rm -f lhrpgpool01
docker run -d --name lhrpgpool01 -h lhrpgpool \
--net=pg-network --ip 172.72.6.66 \
-p 19999:9999 -p 19898:9898 \
-v /sys/fs/cgroup:/sys/fs/cgroup \
--privileged=true lhrbest/lhrpgpool:4.2.2_01 \
/usr/sbin/init
docker network connect bridge lhrpgpool01
docker restart lhrpgpool01
docker exec -it lhrpgpool01 bash
以下所有操作均在pgsql用户执行。
cat >> /postgresql/pgpool/etc/pgpool.conf <<"EOF"
# - Backend Connection Settings -
backend_hostname0 = '172.72.6.61'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = '/pg13/pgdata'
backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_application_name0 = 'lhrrepmgr64361'
backend_hostname1 = '172.72.6.62'
backend_port1 = 5432
backend_weight1 = 1
backend_data_directory1 = '/pg13/pgdata'
backend_flag1 = 'ALLOW_TO_FAILOVER'
backend_application_name1 = 'lhrrepmgr64362'
backend_hostname2 = '172.72.6.63'
backend_port2 = 5432
backend_weight2 = 1
backend_data_directory2 = '/pg13/pgdata'
backend_flag2 = 'ALLOW_TO_FAILOVER'
backend_application_name2 = 'lhrrepmgr64363'
EOF
psql -U postgres -h 192.168.66.35 -p64361
create role nobody login encrypted password 'lhr';
create role lhr login encrypted password 'lhr';
create role pgpool login encrypted password 'lhr';
grant postgres to nobody,lhr,pgpool;
在 PostgreSQL 里没有区分用户和角色的概念,CREATE USER 为 CREATE ROLE 的别名,这两个命令几乎是完全相同的,唯一的区别是”CREATE USER”命令创建的用户的 LOGIN 属性默认为 on , 而 CREATE ROLE 命令创建的用户的 NOLOGIN 属性默认为 on。
systemctl restart pgpool
systemctl status pgpool
[pgsql@lhrpgpool ~]$ psql -U pgpool -h 192.168.66.35 -p 19999 -d postgres
psql (13.2)
Type "help" for help.
postgres=> show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay | replication_state | replication_sync_state | last_status_change
---------+-------------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+---------------------
0 | 172.72.6.61 | 5432 | up | 0.333333 | standby | 0 | false | 0 | | | 2021-04-29 17:40:28
1 | 172.72.6.62 | 5432 | up | 0.333333 | primary | 0 | false | 0 | | | 2021-04-29 17:40:28
2 | 172.72.6.63 | 5432 | up | 0.333333 | standby | 0 | true | 0 | | | 2021-04-29 17:40:28
(3 rows)
repmgr -f /pg13/pg13/repmgr.conf cluster show
repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
repmgr -f /pg13/pg13/repmgr.conf cluster show
执行过程:
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | standby | running | lhrrepmgr64362 | default | 100 | 12 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | primary | * running | | default | 100 | 12 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64362 | default | 100 | 12 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64362 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf standby switchover --siblings-follow --force-rewind
NOTICE: executing switchover on node "lhrrepmgr64361" (ID: 1)
NOTICE: local node "lhrrepmgr64361" (ID: 1) will be promoted to primary; current primary "lhrrepmgr64362" (ID: 2) will be demoted to standby
NOTICE: stopping current primary node "lhrrepmgr64362" (ID: 2)
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64362" (ID: 2)
DETAIL: executing server command "/pg13/pg13/bin/pg_ctl -D '/pg13/pgdata' -W -m fast stop"
INFO: checking for primary shutdown; 1 of 60 attempts ("shutdown_check_timeout")
INFO: checking for primary shutdown; 2 of 60 attempts ("shutdown_check_timeout")
NOTICE: current primary has been cleanly shut down at location 1/22000028
NOTICE: promoting standby to primary
DETAIL: promoting server "lhrrepmgr64361" (ID: 1) using pg_promote()
NOTICE: waiting up to 60 seconds (parameter "promote_check_timeout") for promotion to complete
NOTICE: STANDBY PROMOTE successful
DETAIL: server "lhrrepmgr64361" (ID: 1) was successfully promoted to primary
NOTICE: issuing CHECKPOINT on node "lhrrepmgr64361" (ID: 1)
ERROR: unable to execute CHECKPOINT
INFO: local node 2 can attach to rejoin target node 1
DETAIL: local node's recovery point: 1/22000028; rejoin target node's fork point: 1/220000A0
NOTICE: setting node 2's upstream to node 1
WARNING: unable to ping "host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2"
DETAIL: PQping() returned "PQPING_NO_RESPONSE"
NOTICE: starting server using "/pg13/pg13/bin/pg_ctl -w -D '/pg13/pgdata' start"
WARNING: node "lhrrepmgr64362" attached in state "startup"
NOTICE: NODE REJOIN successful
DETAIL: node 2 is now attached to node 1
WARNING: node "lhrrepmgr64362" attached in state "startup"
INFO: waiting for node "lhrrepmgr64362" (ID: 2) to connect to new primary; 1 of max 60 attempts (parameter "node_rejoin_timeout")
DETAIL: node "lhrrepmgr64361" (ID: 2) is currrently attached to its upstream node in state "startup"
NOTICE: node "lhrrepmgr64361" (ID: 1) promoted to primary, node "lhrrepmgr64362" (ID: 2) demoted to standby
NOTICE: executing STANDBY FOLLOW on 2 of 2 siblings
INFO: node 4 received notification to follow node 1
INFO: STANDBY FOLLOW successfully executed on all reachable sibling nodes
NOTICE: switchover was successful
DETAIL: node "lhrrepmgr64361" is now primary and node "lhrrepmgr64362" is attached as standby
NOTICE: STANDBY SWITCHOVER has completed successfully
[pg13@lhrrepmgr64361 ~]$
[pg13@lhrrepmgr64361 ~]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
ID | Name | Role | Status | Upstream | Location | Priority | Timeline | Connection string
----+----------------+---------+-----------+----------------+----------+----------+----------+---------------------------------------------------------------------------
1 | lhrrepmgr64361 | primary | * running | | default | 100 | 13 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
2 | lhrrepmgr64362 | standby | running | lhrrepmgr64361 | default | 100 | 12 | host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2
3 | lhrrepmgr64363 | standby | running | lhrrepmgr64361 | default | 100 | 12 | host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2
4 | lhrrepmgr64364 | witness | * running | lhrrepmgr64361 | default | 0 | n/a | host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2
[pg13@lhrrepmgr64361 ~]$
使用读写分离测试:
C:\Users\lhrxxt>psql -U pgpool -h 192.168.66.35 -p 19999 -d postgres
Password for user pgpool:
psql (13.2)
Type "help" for help.
postgres=> show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay | replication_state | replication_sync_state | last_status_change
---------+-------------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+---------------------
0 | 172.72.6.61 | 5432 | up | 0.333333 | primary | 0 | true | 0 | | | 2021-04-30 11:17:30
1 | 172.72.6.62 | 5432 | up | 0.333333 | standby | 0 | false | 0 | | | 2021-04-30 11:17:30
2 | 172.72.6.63 | 5432 | up | 0.333333 | standby | 0 | false | 0 | | | 2021-04-30 11:14:39
(3 rows)
可以看到,状态是正确的。
其它情况不再做测试,想学习更多内容,可以私聊麦老师。
1、由于主从切换需要启动数据库,所以,在整个环境中,所有的PG数据库均不能使用systemctl来管理,否则切换会出现问题。
2、若要清除节点的注册信息,也可以进入主库中,操作repmgr.nodes表信息。
本文结束。