keepalive实现oracle集群,Oracle ADG + Keepalived 切换演练

客户的一套生产环境采用的架构是Oracle ADG + Keepalived，近期需要进行切换演练，要求我这边保障。ADG本身切换倒没啥可说的，但引入keepalived软件，就需要提前研究下这个架构。其实看了下环境配置，整体思路也非常简单，说白了就是利用keepalived软件引入一个VIP，应用侧只需配置连接这个VIP即可。

依据当前生产环境架构模拟了一套自己的测试环境。

1.Keepalived相关配置

关于Keepalived软件的配置和编译安装，可以参考之前《MySQL主主+Keepalived架构安装部署》中Keepalived安装部署章节。

除了利用keepalived软件引入一个VIP，还有一些配置和脚本，脱敏如下：

——————————————————–

–节点1(192.168.1.124)keepalived.conf文件内容：

——————————————————–

[[email protected] ~]# cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived

vrrp_script chk_dg_stats {

script “/etc/keepalived/check_dataguard.sh”

interval 2

weight -5

fall 2

rise 1

}

vrrp_instance VI_1 {

state MASTER

interface eth0

mcast_src_ip 192.168.1.124

virtual_router_id 131

priority 101

inopreempt

advert_int 1

authentication {

auth_type PASS

auth_pass 888888

}

virtual_ipaddress {

192.168.1.131

}

track_script {

chk_dg_stats

}

}

——————————————————–

–节点2(192.168.1.125)keepalived.conf文件内容：

——————————————————–

[[email protected] ~]# cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived

vrrp_script chk_dg_stats {

script “/etc/keepalived/check_dataguard.sh”

interval 2

weight -5

fall 2

rise 1

}

vrrp_instance VI_1 {

state BACKUP

interface eth0

mcast_src_ip 192.168.1.125

virtual_router_id 131

priority 99

inopreempt

advert_int 1

authentication {

auth_type PASS

auth_pass 888888

}

virtual_ipaddress {

192.168.1.131

}

track_script {

chk_dg_stats

}

}

——————————————————–

–所有节点配置脚本check_dataguard.sh，并确认具有x执行权限：

——————————————————–

# cat /etc/keepalived/check_dataguard.sh

#!/bin/bash

dbstats=`ps -ef | grep ora_smon | grep -v grep | wc -l`

dgstats=`ps -ef | grep ora_mrp | grep -v grep | wc -l`

if [ “${dbstats}” -eq 0 ]; then

/etc/init.d/keepalived stop

elif [[ “${dbstats}” -gt 0 ]] && [[ “${dgstats}” -gt 0 ]]; then

/etc/init.d/keepalived stop

fi

说明：脚本check_dataguard.sh主要通过对ora_smon和ora_mrp进程的监控，判断哪种场景下该关闭keepalived服务：

场景1:当不存在ora_smon进程时(数据库实例Crash)；

场景2:存在ora_smon进程同时存在ora_mrp进程时(已启动mrp进程的备库)。

–添加x执行权限：

chmod u+x /etc/keepalived/check_dataguard.sh

[[email protected] ~]# ls -l /etc/keepalived/check_dataguard.sh

-rwxr–r–. 1 root root 282 Jul 14 22:35 /etc/keepalived/check_dataguard.sh

[[email protected] ~]# ls -l /etc/keepalived/check_dataguard.sh

-rwxr–r–. 1 root root 281 Jul 14 22:36 /etc/keepalived/check_dataguard.sh

2.ADG手工切换步骤

1)在switchover正式切换前先在主库上手工切换几次日志，确认DG备库同步正常：

–PRIMARY(主库192.168.1.124)切换几次日志:

SQL>

alter system switch logfile;

alter system switch logfile;

alter system switch logfile;

–Standby (备库192.168.1.125)需确认同步正常没有延迟:

SQL>

select * from v$dataguard_stats;

2)主库切换为备库

— 在PRIMARY(主库192.168.1.124)查询，确认可切换为备库：

select OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS from v$database;

— 在PRIMARY(主库192.168.1.124)操作，切换为备库：

ALTER DATABASE COMMIT TO SWITCHOVER TO STANDBY WITH SESSION SHUTDOWN;

3)备库切换为主库

— 在Standby(备库192.168.1.125)查询，确认可切换为主库：

select OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS from v$database;

— 在Standby(备库192.168.1.125)操作，切换为主库(根据SWITCHOVER_STATUS值确认用下面哪个命令)：

ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;

ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN;

4)新主库open，新备库启动并开启MRP，新主库启动keepalived服务

–NEW PRIMARY(新主库192.168.1.125)数据库从mount启动到open状态:

ALTER DATABASE OPEN;

–NEW STANDBY(新备库192.168.1.124)数据库startup启动，开启DG日志应用:

STARTUP

RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT;

–确认NEW STANDBY(新备库192.168.1.124)DG同步正常，没有延迟：

SQL>

select * from v$dataguard_stats;

5) 新主库启动keepalived服务

–NEW PRIMARY(新主库192.168.1.125)OS层root用户启动keepalived服务：

# /etc/init.d/keepalived start

注意：当演练结束后，若需要switchover主备再次切换，只需要按上面规范步骤重复操作即可(注意主备角色的转换)。

3.VIP和监听的关系

源于最早的一次面试，两个节点的RAC，节点1主机Crash，此时应用通过节点1的VIP是否可以连接到数据库什么/p>

我们都知道节点1主机Crash，其VIP会自动漂移节点2，ping这个IP也是通的，但是通过其连接数据库却不行！会 一个没有监听(ORA-12541: TNS:no listener)的错误。

具体可参考：

RAC 某节点不可用时，对应VIP是否可用

那这里的环境，同样是VIP的设置，为何却可以通过VIP(192.168.1.131)连接呢/p>

[[email protected] ~]$ sqlplus [email protected]/demo as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Tue Jul 14 23:45:23 2020

Copyright (c) 1982, 2013, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 – 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>

实际验证，是因为这里主备库的监听配置统一都是主机名:

[[email protected] admin]$ cat listener.ora

# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora

# Generated by Oracle configuration tools.

LISTENER =

(DESCRIPTION_LIST =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))

(ADDRESS = (PROTOCOL = TCP)(HOST = test04)(PORT = 1521))

)

)

ADR_BASE_LISTENER = /u01/app/oracle

[[email protected] admin]$ cat listener.ora

# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora

# Generated by Oracle configuration tools.

LISTENER =

(DESCRIPTION_LIST =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))

(ADDRESS = (PROTOCOL = TCP)(HOST = test05)(PORT = 1521))

)

)

ADR_BASE_LISTENER = /u01/app/oracle

SID_LIST_LISTENER =

(SID_LIST =

(SID_DESC =

(GLOBAL_DBNAME = jingyus)

(ORACLE_HOME = /u01/app/oracle/product/11.2.0/dbhome_1)

(SID_NAME = jingyu)

)

)

如果将主机名修改为具体的IP地址，则测试同样会 错(ORA-12541: TNS:no listener)。

原文：https://www.cnblogs.com/jyzhao/p/13303202.html

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