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pgpool mysql_PGPool-II+PG流复制实现HA主备切换

發(fā)布時(shí)間：2023/12/31 数据库 33 豆豆

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基于PG的流復(fù)制能實(shí)現(xiàn)熱備切換，但是是要手動(dòng)建立觸發(fā)文件實(shí)現(xiàn)，對(duì)于一些HA場(chǎng)景來說，需要當(dāng)主機(jī)down了后，備機(jī)自動(dòng)切換，經(jīng)查詢資料知道pgpool-II可以實(shí)現(xiàn)這種功能。本文基于PG流復(fù)制基礎(chǔ)上，以pgpool-II實(shí)現(xiàn)主備切換。在配置pgpool之前需分別在兩臺(tái)規(guī)劃機(jī)上安裝好pg數(shù)據(jù)庫，且配置好了流復(fù)制環(huán)境，關(guān)于流復(fù)制配置參考前文：http://www.jianshu.com/p/12bc931ebba3。

pgpool雙機(jī)集群架構(gòu)圖.png

基于PGPool的雙機(jī)集群如上圖所示：pg主節(jié)點(diǎn)和備節(jié)點(diǎn)實(shí)現(xiàn)流復(fù)制熱備，pgpool1，pgpool2作為中間件，將主備pg節(jié)點(diǎn)加入集群，實(shí)現(xiàn)讀寫分離，負(fù)載均衡和HA故障自動(dòng)切換。兩pgpool節(jié)點(diǎn)可以委托一個(gè)虛擬ip節(jié)點(diǎn)作為應(yīng)用程序訪問的地址，兩節(jié)點(diǎn)之間通過watchdog進(jìn)行監(jiān)控，當(dāng)pgpool1宕機(jī)時(shí)，pgpool2會(huì)自動(dòng)接管虛擬ip繼續(xù)對(duì)外提供不間斷服務(wù)。

一主機(jī)規(guī)劃

主機(jī)名 | IP | 角色 | 端口

:----:|:----:|:----:|:----:|:----:|:----:

master| 192.168.0.108 |PGMaster|5432

| 192.168.0.108|pgpool1|9999

slave|192.168.0.109|PGSlave|5432

| 192.168.0.109|pgpool2|9999

vip|192.168.0.150|虛擬ip|9999

建立好主機(jī)規(guī)劃之后，在master，slave上兩臺(tái)機(jī)器設(shè)置下host

[root@localhost ~]# vi .bashrc

#編輯內(nèi)容如下：

192.168.0.108 master

192.168.0.109 slave

192.168.0.150 vip

二配置ssh秘鑰

在master,slave機(jī)器上都生成ssh如下：

[root@localhost ~]# su - postgres

[postgres@localhost ~]$ ssh-keygen -t rsa

[postgres@localhost ~]$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys

[postgres@localhost ~]$ chmod 600 ~/.ssh/authorized_keys

分別將master的公鑰復(fù)制到slave，slave的公鑰復(fù)制到master。

#master端

[postgres@localhost ~]$ scp ~/.ssh/authorized_keys postgres@slave:~/.ssh/

#slave端

[postgres@localhost ~]$ scp ~/.ssh/authorized_keys postgres@master:~/.ssh/

驗(yàn)證下ssh配置是否成功

#master端

[postgres@slave ~]$ ssh postgres@slave

Last login: Tue Dec 20 21:22:50 2016 from master

#slave端

[postgres@slave ~]$ ssh postgres@master

Last login: Tue Dec 20 21:22:50 2016 from slave

證明ssh信任關(guān)系配置成功。

三安裝pgpool

# 下載pgpool

[root@master opt]# wget http://www.pgpool.net/mediawiki/images/pgpool-II-3.6.0.tar.gz

# 解壓

[root@master opt]# tar -zxvf pgpool-II-3.6.0.tar.gz

# 文件權(quán)限設(shè)置為postgres(其實(shí)并非一定裝在postgres賬戶，只不過之前ssh設(shè)置都在postgres下，為了方便)

[root@master opt]# chown -R postgres.postgres /opt/pgpool-II-3.6.0

[root@master ~]# su - postgres

[postgres@master opt]$ cd pgpool-II-3.6.0

[postgres@master pgpool-II-3.6.0]$ ./configure –prefix=/opt/pgpool -with-pgsql=path -with-pgsql=/home/postgres

[postgres@master pgpool-II-3.6.0]$ make

[postgres@master pgpool-II-3.6.0]$ make install

安裝pgpool相關(guān)函數(shù)，并非強(qiáng)制，可選安裝，為了系統(tǒng)穩(wěn)定，建議安裝

安裝pg_reclass,pg_recovery

[postgres@master pgpool-II-3.6.0]$ cd src/sql

[postgres@master sql]$ make

[postgres@master sql]$ make install

[postgres@master sql]$ psql -f insert_lock.sql

安裝全部結(jié)束。

四配置pgpool

4.1 配置pgpool環(huán)境變量

pgpool裝在了postgres賬戶下，在該賬戶中添加環(huán)境變量，master,slave節(jié)點(diǎn)都執(zhí)行。

[postgres@master ~]$ cd /home/postgres

[postgres@master ~]$ vim .bashrc

#編輯內(nèi)容如下

PGPOOLHOME=/opt/pgpool

export PGPOOLHOME

PATH=$PATH:$HOME/.local/bin:$HOME/bin:$PGHOME/bin:$PGPOOLHOME/bin

export PATH

4.2 配置pool_hba.conf

pool_hba.conf是對(duì)登錄用戶進(jìn)行驗(yàn)證的，要和pg的pg_hba.conf保持一致，要么都是trust，要么都是md5驗(yàn)證方式，這里采用了md5驗(yàn)證方式如下設(shè)置：

[postgres@master ~]$ cd /opt/pgpool/etc

[postgres@etc~]$ cp pool_hba.conf.sample pool_hba.conf

[postgres@etc~]$ vim pool_hba.conf

#編輯內(nèi)容如下

# "local" is for Unix domain socket connections only

local all all md5

# IPv4 local connections:

host all all 0.0.0.0/0 md5

host all all 0/0 md5

4.3 配置pcp.conf

pcp.conf配置用于pgpool自己登陸管理使用的，一些操作pgpool的工具會(huì)要求提供密碼等，配置如下：

[postgres@master ~]$ cd /opt/pgpool/etc

[postgres@etc~]$ cp pcp.conf.sample pcp.conf

# 使用pg_md5生成配置的用戶名密碼

[postgres@etc~]$ pg_md5 nariadmin

6b07583ba8af8e03043a1163147faf6a

#pcp.conf是pgpool管理器自己的用戶名和密碼，用于管理集群。

[postgres@etc~]$ vim pcp.conf

#編輯內(nèi)容如下

postgres:6b07583ba8af8e03043a1163147faf6a

#保存退出！

#在pgpool中添加pg數(shù)據(jù)庫的用戶名和密碼

[postgres@etc~]$ pg_md5 -p -m -u postgres pool_passwd

#數(shù)據(jù)庫登錄用戶是postgres,這里輸入登錄密碼，不能出錯(cuò)

#輸入密碼后，在pgpool/etc目錄下會(huì)生成一個(gè)pool_passwd文件

4.4 配置系統(tǒng)命令權(quán)限

配置 ifconfig, arping 執(zhí)行權(quán)限，執(zhí)行failover_stream.sh需要用到，可以讓其他普通用戶執(zhí)行。

[root@master ~]# chmod u+s /sbin/ifconfig

[root@master ~]# chmod u+s /usr/sbin

4.5 配置pgpool.conf

查看本機(jī)網(wǎng)卡，配置后面的delegate_IP需要

[postgres@etc~]$ ifconfig

網(wǎng)卡名稱.png

配置master上的pgpool.conf:

[postgres@master ~]$ cd /opt/pgpool/etc

[postgres@etc~]$ cp pgpool.conf.sample pgpool.conf

[postgres@etc~]$ vim pgpool.conf

編輯內(nèi)容如下：

# CONNECTIONS

listen_addresses = '*'

port = 9999

pcp_listen_addresses = '*'

pcp_port = 9898

# - Backend Connection Settings -

backend_hostname0 = 'master'

backend_port0 = 5432

backend_weight0 = 1

backend_data_directory0 = '/home/postgres/data'

backend_flag0 = 'ALLOW_TO_FAILOVER'

backend_hostname1 = 'slave'

backend_port1 = 5432

backend_weight1 = 1

backend_data_directory1 = '/home/postgres/data'

backend_flag1 = 'ALLOW_TO_FAILOVER'

# - Authentication -

enable_pool_hba = on

pool_passwd = 'pool_passwd'

# FILE LOCATIONS

pid_file_name = '/opt/pgpool/pgpool.pid'

replication_mode = off

load_balance_mode = on

master_slave_mode = on

master_slave_sub_mode = 'stream'

sr_check_period = 5

sr_check_user = 'repuser'

sr_check_password = 'repuser'

sr_check_database = 'postgres'

#------------------------------------------------------------------------------

# HEALTH CHECK 健康檢查

#------------------------------------------------------------------------------

health_check_period = 10 # Health check period

# Disabled (0) by default

health_check_timeout = 20

# Health check timeout

# 0 means no timeout

health_check_user = 'postgres'

# Health check user

health_check_password = 'nariadmin' #數(shù)據(jù)庫密碼

# Password for health check user

health_check_database = 'postgres'

#必須設(shè)置，否則primary數(shù)據(jù)庫down了，pgpool不知道，不能及時(shí)切換。從庫流復(fù)制還在連接數(shù)據(jù)，報(bào)連接失敗。

#只有下次使用pgpool登錄時(shí)，發(fā)現(xiàn)連接不上，然后報(bào)錯(cuò)，這時(shí)候，才知道掛了，pgpool進(jìn)行切換。

#主備切換的命令行配置

#------------------------------------------------------------------------------

# FAILOVER AND FAILBACK

#------------------------------------------------------------------------------

failover_command = '/opt/pgpool/failover_stream.sh %H '

#------------------------------------------------------------------------------

# WATCHDOG

#------------------------------------------------------------------------------

# - Enabling -

use_watchdog = on

# - Watchdog communication Settings -

wd_hostname = 'master'

# Host name or IP address of this watchdog

# (change requires restart)

wd_port = 9000

# port number for watchdog service

# (change requires restart)

# - Virtual IP control Setting -

delegate_IP = 'vip'

# delegate IP address

# If this is empty, virtual IP never bring up.

# (change requires restart)

if_cmd_path = '/sbin'

# path to the directory where if_up/down_cmd exists

# (change requires restart)

if_up_cmd = 'ifconfig eth1:0 inet $_IP_$ netmask 255.255.255.0'

# startup delegate IP command

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

if_down_cmd = 'ifconfig eth1:0 down'

# shutdown delegate IP command

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

# -- heartbeat mode --

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 = 'slave'

# 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)

heartbeat_device0 = 'eth1'

# Name of NIC device (such like 'eth0')

# used for sending/receiving heartbeat

# signal to/from destination 0.

# This works only when this is not empty

# and pgpool has root privilege.

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

# - Other pgpool Connection Settings -

other_pgpool_hostname0 = 'slave' #對(duì)端

# Host name or IP address to connect to for other pgpool 0

# (change requires restart)

other_pgpool_port0 = 9999

# Port number for othet pgpool 0

# (change requires restart)

other_wd_port0 = 9000

# Port number for othet watchdog 0

# (change requires restart)

配置slave上的pgpool.conf:

# CONNECTIONS

listen_addresses = '*'

port = 9999

pcp_listen_addresses = '*'

pcp_port = 9898

# - Backend Connection Settings -

backend_hostname0 = 'master'

backend_port0 = 5432

backend_weight0 = 1

backend_data_directory0 = '/home/postgres/data'

backend_flag0 = 'ALLOW_TO_FAILOVER'

backend_hostname1 = 'slave'

backend_port1 = 5432

backend_weight1 = 1

backend_data_directory1 = '/home/postgres/data'

backend_flag1 = 'ALLOW_TO_FAILOVER'

# - Authentication -

enable_pool_hba = on

pool_passwd = 'pool_passwd'

# FILE LOCATIONS

pid_file_name = '/opt/pgpool/pgpool.pid'

replication_mode = off

load_balance_mode = on

master_slave_mode = on

master_slave_sub_mode = 'stream'

sr_check_period = 5

sr_check_user = 'repuser'

sr_check_password = 'repuser'

sr_check_database = 'postgres'

#------------------------------------------------------------------------------

# HEALTH CHECK 健康檢查

#------------------------------------------------------------------------------

health_check_period = 10 # Health check period

# Disabled (0) by default

health_check_timeout = 20

# Health check timeout

# 0 means no timeout

health_check_user = 'postgres'

# Health check user

health_check_password = 'nariadmin' #數(shù)據(jù)庫密碼

# Password for health check user

health_check_database = 'postgres'

#必須設(shè)置，否則primary數(shù)據(jù)庫down了，pgpool不知道，不能及時(shí)切換。從庫流復(fù)制還在連接數(shù)據(jù)，報(bào)連接失敗。

#只有下次使用pgpool登錄時(shí)，發(fā)現(xiàn)連接不上，然后報(bào)錯(cuò)，這時(shí)候，才知道掛了，pgpool進(jìn)行切換。

#主備切換的命令行配置

#------------------------------------------------------------------------------

# FAILOVER AND FAILBACK

#------------------------------------------------------------------------------

failover_command = '/opt/pgpool/failover_stream.sh %H '

#------------------------------------------------------------------------------

# WATCHDOG

#------------------------------------------------------------------------------

# - Enabling -

use_watchdog = on

# - Watchdog communication Settings -

wd_hostname = 'slave' #本端

# Host name or IP address of this watchdog

# (change requires restart)

wd_port = 9000

# port number for watchdog service

# (change requires restart)

# - Virtual IP control Setting -

delegate_IP = 'vip'

# delegate IP address

# If this is empty, virtual IP never bring up.

# (change requires restart)

if_cmd_path = '/sbin'

# path to the directory where if_up/down_cmd exists

# (change requires restart)

if_up_cmd = 'ifconfig eth1:0 inet $_IP_$ netmask 255.255.255.0'

# startup delegate IP command

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

if_down_cmd = 'ifconfig eth1:0 down'

# shutdown delegate IP command

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

# -- heartbeat mode --

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 = 'master' #對(duì)端

# 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)

heartbeat_device0 = 'eth1'

# Name of NIC device (such like 'eth0')

# used for sending/receiving heartbeat

# signal to/from destination 0.

# This works only when this is not empty

# and pgpool has root privilege.

# (change requires restart)

# eth1根據(jù)現(xiàn)場(chǎng)機(jī)器改掉

# - Other pgpool Connection Settings -

other_pgpool_hostname0 = 'master' #對(duì)端

# Host name or IP address to connect to for other pgpool 0

# (change requires restart)

other_pgpool_port0 = 9999

# Port number for othet pgpool 0

# (change requires restart)

other_wd_port0 = 9000

# Port number for othet watchdog 0

# (change requires restart)

配置文件里，故障處理配置的是failover_command = '/opt/pgpool/failover_stream.sh %H '，因此，需要在/opt/pgpool目錄中寫個(gè)failover_stream.sh腳本：

[postgres@master ~]$ cd /opt/pgpool

[postgres@pgpool~]$ touch failover_stream.sh

[postgres@pgpool~]$ vim failover_stream.sh

注意這里使用了promote 而不是觸發(fā)文件，觸發(fā)文件來回切換有問題，編輯內(nèi)容如下：

#! /bin/sh

# Failover command for streaming replication.

# Arguments: $1: new master hostname.

new_master=$1

trigger_command="$PGHOME/bin/pg_ctl promote -D $PGDATA"

# Prompte standby database.

/usr/bin/ssh -T $new_master $trigger_command

exit 0;

如果是其他用戶創(chuàng)建的，需要賦予postgres可執(zhí)行權(quán)限，例如

[root@opt ~]$ chown -R postgres.postgres /opt/pgpool

[root@opt ~]]$ chmod 777 /opt/pgpool/failover_stream.sh

五 PGPool集群管理

啟動(dòng)之前在master,slave節(jié)點(diǎn)創(chuàng)建兩個(gè)日志文件：

[root@master ~]# mkdir /var/log/pgpool

[root@master ~]# chown -R postgres.postgres /var/log/pgpool

[root@master ~]# mkdir /var/run/pgpool

[root@master ~]# chown -R postgres.postgres /var/run/pgpool

5.1 啟動(dòng)集群

分別啟動(dòng)primary,standby的pg庫

#master上操作

[postgres@master ~]$ pg_ctl start -D $PGDATA

#slave上操作

[postgres@slave ~]$ pg_ctl start -D $PGDATA

分別啟動(dòng)pgpool命令：

#master上操作

# -D會(huì)重新加載pg nodes的狀態(tài)如down或up

[postgres@master ~]$ pgpool -n -d -D > /var/log/pgpool/pgpool.log 2>&1 &

[1] 3557

#slave上操作

[postgres@slave ~]$ pgpool -n -d -D > /var/log/pgpool/pgpool.log 2>&1 &

[1] 3557

注意快速終止pgpool命令：

[postgres@ ~]$ pgpool -m fast stop

啟動(dòng)pgpool后，查看集群節(jié)點(diǎn)狀態(tài):

[postgres@master ~]$ psql -h vip -p 9999

psql (9.6.1)

#提示輸入密碼：

Type "help" for help.

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | up | 0.500000 | primary | 0 | false | 0

1 | slave | 5432 | up | 0.500000 | standby | 0 | true | 0

(2 rows)

#在slave上節(jié)點(diǎn)也是psql -h vip -p 9999，雙pgpool使用虛擬ip，做到高可用。

發(fā)現(xiàn)當(dāng)前主備節(jié)點(diǎn)都是正常的up狀態(tài)。

5.2 Pgpool的HA

5.2.1 模擬master端pgpool宕機(jī)

在master節(jié)點(diǎn)上停止pgpool服務(wù)

[postgres@master ~]$ pgpool -m fast stop

#稍等片刻后，訪問集群

[postgres@master ~]$ psql -h vip -p 9999

psql (9.6.1)

#提示輸入密碼：

Type "help" for help.

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | up | 0.500000 | primary | 0 | false | 0

1 | slave | 5432 | up | 0.500000 | standby | 0 | true | 0

(2 rows)

#訪問成功，在master節(jié)點(diǎn)上的pgpool宕機(jī)后，由slave節(jié)點(diǎn)的pgpool接管vip和集群服務(wù)，并未中斷應(yīng)用訪問。

#在master上重新啟動(dòng)pgpool后，定制slave上的pgpool服務(wù)，結(jié)果一樣。

5.2.2模擬master端pg primary宕機(jī)

[postgres@master ~]$ pg_ctl stop

#master端打印

2017-07-24 18:52:37.751 PDT [28154] STATEMENT: SELECT pg_current_xlog_location()

2017-07-24 18:52:37.760 PDT [2553] LOG: received fast shutdown request

2017-07-24 18:52:37.760 PDT [2553] LOG: aborting any active transactions

2017-07-24 18:52:37.762 PDT [28156] FATAL: canceling authentication due to timeout

2017-07-24 18:52:37.763 PDT [2555] LOG: shutting down

2017-07-24 18:52:37.768 PDT [28158] FATAL: the database system is shutting down

2017-07-24 18:52:37.775 PDT [28159] FATAL: the database system is shutting down

2017-07-24 18:52:39.653 PDT [2553] LOG: database system is shut down

#slave端打印

2017-07-24 18:52:41.455 PDT [2614] LOG: invalid record length at 0/2A000098: wanted 24, got 0

2017-07-24 18:52:47.333 PDT [2614] LOG: received promote request

2017-07-24 18:52:47.333 PDT [2614] LOG: redo done at 0/2A000028

2017-07-24 18:52:47.333 PDT [2614] LOG: last completed transaction was at log time 2017-07-24 18:17:00.946759-07

2017-07-24 18:52:47.336 PDT [2614] LOG: selected new timeline ID: 10

2017-07-24 18:52:47.841 PDT [2614] LOG: archive recovery complete

2017-07-24 18:52:47.851 PDT [2613] LOG: database system is ready to accept connections

#日志清楚看到主機(jī)down機(jī)了，slave切換了。

#稍等片刻后，訪問集群

[postgres@master ~]$ psql -h vip -p 9999

Password:

psql (10beta1)

Type "help" for help.

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | down | 0.500000 | standby | 0 | false | 0

1 | slave | 5432 | up | 0.500000 | primary | 0 | true | 0

(2 rows)

#slave已經(jīng)被切換成primary，且master節(jié)點(diǎn)狀態(tài)是down

5.2.3 修復(fù)master節(jié)點(diǎn)重新加入集群

master節(jié)點(diǎn)down機(jī)后，slave節(jié)點(diǎn)已經(jīng)被切換成了primary，修復(fù)好master后應(yīng)重新加入節(jié)點(diǎn)，作為primary的standby。

修復(fù)master端并啟動(dòng)操作：

[postgres@master ~]$ cd $PGDATA

[postgres@master data]$ mv recovery.done recovery.conf #一定要把.done改成.conf

[postgres@master data]$ pg_ctl start

在pgpool集群中加入節(jié)點(diǎn)狀態(tài):

#注意master的node_id是0，所以-n 0

[postgres@master data]$ pcp_attach_node -d -U postgres -h vip -p 9898 -n 0

#提示輸入密碼，輸入pcp管理密碼。

#查看當(dāng)前狀態(tài)

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | up | 0.500000 | standby | 0 | false | 0

1 | slave | 5432 | up | 0.500000 | primary | 0 | true | 0

(2 rows)

5.2.4 主機(jī)直接down機(jī)

當(dāng)前slave節(jié)點(diǎn)是primay，我們直接將slave服務(wù)器直接關(guān)機(jī)后，發(fā)現(xiàn)實(shí)現(xiàn)了主備切換，slave已經(jīng)down了，而master已經(jīng)被切換成了primary：

[postgres@master ~]$ psql -h vip -p 9999

Password:

psql (10beta1)

Type "help" for help.

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | up | 0.500000 | primary | 0 | true | 0

1 | slave | 5432 | down | 0.500000 | standby | 0 | false | 0

(2 rows)

5.3 數(shù)據(jù)線同步

在主備切換時(shí)，修復(fù)節(jié)點(diǎn)并重啟后，由于primary數(shù)據(jù)發(fā)生變化，或修復(fù)的節(jié)點(diǎn)數(shù)據(jù)發(fā)生變化再按照流復(fù)制模式加入集群，很可能報(bào)時(shí)間線不同步錯(cuò)誤：

#slave機(jī)器重啟后，由于master或slave數(shù)據(jù)不同步產(chǎn)生了

[postgres@slave data]$ mv recovery.done recovery.conf

[postgres@slave data]$ pg_ctl start

waiting for server to start....2017-07-24 19:31:44.563 PDT [2663] LOG: listening on IPv4 address "0.0.0.0", port 5432

2017-07-24 19:31:44.563 PDT [2663] LOG: listening on IPv6 address "::", port 5432

2017-07-24 19:31:44.565 PDT [2663] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"

2017-07-24 19:31:44.584 PDT [2664] LOG: database system was shut down at 2017-07-24 19:31:30 PDT

2017-07-24 19:31:44.618 PDT [2664] LOG: entering standby mode

2017-07-24 19:31:44.772 PDT [2664] LOG: consistent recovery state reached at 0/2D000098

2017-07-24 19:31:44.772 PDT [2663] LOG: database system is ready to accept read only connections

2017-07-24 19:31:44.772 PDT [2664] LOG: invalid record length at 0/2D000098: wanted 24, got 0

2017-07-24 19:31:44.798 PDT [2668] LOG: fetching timeline history file for timeline 11 from primary server

2017-07-24 19:31:44.826 PDT [2668] FATAL: could not start WAL streaming: ERROR: requested starting point 0/2D000000 on timeline 10 is not in this server's history

DETAIL: This server's history forked from timeline 10 at 0/2B0001B0.

2017-07-24 19:31:44.826 PDT [2664] LOG: new timeline 11 forked off current database system timeline 10 before current recovery point 0/2D000098

done

產(chǎn)生這種情況，需要根據(jù)pg_rewind工具同步數(shù)據(jù)時(shí)間線，具體分5步走。

5.3.1停掉需要做同步的節(jié)點(diǎn)pg服務(wù)

[postgres@slave ] pg_ctl stop

5.3.2 同步master節(jié)點(diǎn)上時(shí)間線

[postgres@slave data]$ pg_rewind --target-pgdata=/home/postgres/data --source-server='host=master port=5432 user=postgres dbname=postgres password=nariadmin'

servers diverged at WAL location 0/2B0001B0 on timeline 10

rewinding from last common checkpoint at 0/2B000108 on timeline 10

Done!

5.3.3 修改pg_hba.conf與 recovery.done文件

#pg_hba.conf與 recovery.done都是同步master上來的，要改成slave自己的

[postgres@slave ] cd $PGDATA

[postgres@slave data]$ mv recovery.done recovery.conf

[postgres@slave data]$ vi pg_hba.conf

#slave改成master(相當(dāng)于slave的流復(fù)制對(duì)端)

host replication repuser master md5

[postgres@slave data]$ vi recovery.conf

#slave改成master(相當(dāng)于slave的流復(fù)制對(duì)端)

primary_conninfo = 'host=master port=5432 user=repuser password=repuser'

5.3.4 重啟pg服務(wù)

[postgres@slave data]$ pg_ctl start

waiting for server to start....2017-07-24 19:47:06.821 PDT [2722] LOG: listening on IPv4 address "0.0.0.0", port 5432

2017-07-24 19:47:06.821 PDT [2722] LOG: listening on IPv6 address "::", port 5432

2017-07-24 19:47:06.907 PDT [2722] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"

2017-07-24 19:47:06.930 PDT [2723] LOG: database system was interrupted while in recovery at log time 2017-07-24 19:25:42 PDT

2017-07-24 19:47:06.930 PDT [2723] HINT: If this has occurred more than once some data might be corrupted and you might need to choose an earlier recovery target.

2017-07-24 19:47:06.961 PDT [2723] LOG: entering standby mode

2017-07-24 19:47:06.966 PDT [2723] LOG: redo starts at 0/2B0000D0

2017-07-24 19:47:06.971 PDT [2723] LOG: consistent recovery state reached at 0/2B01CA30

2017-07-24 19:47:06.972 PDT [2722] LOG: database system is ready to accept read only connections

2017-07-24 19:47:06.972 PDT [2723] LOG: invalid record length at 0/2B01CA30: wanted 24, got 0

2017-07-24 19:47:06.982 PDT [2727] LOG: started streaming WAL from primary at 0/2B000000 on timeline 11

done

server started

5.3.5 重新加入集群

#注意slave的node_id是1，所以-n 1

[postgres@slave data]$ pcp_attach_node -d -U postgres -h vip -p 9898 -n 1

Password: #提示輸入密碼，輸入pcp管理密碼。

DEBUG: recv: tos="m", len=8

DEBUG: recv: tos="r", len=21

DEBUG: send: tos="C", len=6

DEBUG: recv: tos="c", len=20

pcp_attach_node -- Command Successful

DEBUG: send: tos="X", len=4

5.3.6 查看集群節(jié)點(diǎn)狀態(tài)

[postgres@slave data]$ psql -h vip -p 9999

Password:

psql (10beta1)

Type "help" for help.

postgres=# show pool_nodes;

---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------

0 | master | 5432 | up | 0.500000 | primary | 0 | true | 0

1 | slave | 5432 | up | 0.500000 | standby | 0 | false | 0

(2 rows)

全部恢復(fù)工作完成。

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