1.输入show命令查看目前集群状态，其中group GRP1为集群的组名，当前主备集群状态正常，SLNNGK实例为primary，SLNNGKBAK为standby
我这里的mode是设置manual手工切换的
show
2022-07-26 09:37:25
#================================================================================#
GROUP OGUID MON_CONFIRM MODE MPP_FLAG
GRP1 453332 FALSE MANUAL FALSE

<<DATABASE GLOBAL INFO:>>
DW_IP MAL_DW_PORT WTIME WTYPE WCTLSTAT WSTATUS INAME INST_OK N_EP N_OK ISTATUS IMODE DSC_STATUS RTYPE RSTAT
192.168.1.135 52141 2022-07-26 09:37:24 GLOBAL VALID OPEN SLNNGK OK 1 1 OPEN PRIMARY DSC_OPEN REALTIME VALID

EP INFO:
INST_IP INST_PORT INST_OK INAME ISTATUS IMODE DSC_SEQNO DSC_CTL_NODE RTYPE RSTAT FSEQ FLSN CSEQ CLSN DW_STAT_FLAG
192.168.1.135 5236 OK SLNNGK OPEN PRIMARY 0 0 REALTIME VALID 377284 424700 377284 424701 NONE

<<DATABASE GLOBAL INFO:>>
DW_IP MAL_DW_PORT WTIME WTYPE WCTLSTAT WSTATUS INAME INST_OK N_EP N_OK ISTATUS IMODE DSC_STATUS RTYPE RSTAT
192.168.1.134 52141 2022-07-26 09:37:24 GLOBAL VALID OPEN SLNNGKBAK OK 1 1 OPEN STANDBY DSC_OPEN REALTIME VALID

EP INFO:
INST_IP INST_PORT INST_OK INAME ISTATUS IMODE DSC_SEQNO DSC_CTL_NODE RTYPE RSTAT FSEQ FLSN CSEQ CLSN DW_STAT_FLAG
192.168.1.134 5236 OK SLNNGKBAK OPEN STANDBY 0 0 REALTIME VALID 62839 424699 62839 424699 NONE

DATABASE(SLNNGKBAK) APPLY INFO FROM (SLNNGK), REDOS_PARALLEL_NUM (1):
DSC_SEQNO[0], (RSEQ, SSEQ, KSEQ)[377283, 377283, 377284], (RLSN, SLSN, KLSN)[424699, 424699, 424700], N_TSK[0], TSK_MEM_USE[512]
REDO_LSN_ARR: (424699)

#================================================================================#

2.登陆监视器
输入login 登陆监视器，然后输入用户名和密码(dameng123)
login
username:sysdba
password:
[monitor] 2022-07-26 09:39:46: Login dmmonitor success!

3.查看可切换节点
输入choose switchover GRP1 查看集群可以切换的节点（GRP_DW为集群的分组名称），通过该命令查看到DW1实例节点可以作为primary节点进行切换。

choose switchover GRP1
Can choose one of the following instances to do switchover:
1: SLNNGKBAK

4.切换节点
输入switchover SLNNGKBAK回车，集群开始进行主备切换
switchover SLNNGKBAK

5.检查是否已经切换
show
2022-07-26 09:42:30
#================================================================================#
GROUP OGUID MON_CONFIRM MODE MPP_FLAG
GRP1 453332 FALSE MANUAL FALSE

<<DATABASE GLOBAL INFO:>>
DW_IP MAL_DW_PORT WTIME WTYPE WCTLSTAT WSTATUS INAME INST_OK N_EP N_OK ISTATUS IMODE DSC_STATUS RTYPE RSTAT
192.168.1.134 52141 2022-07-26 09:42:30 GLOBAL VALID OPEN SLNNGKBAK OK 1 1 OPEN PRIMARY DSC_OPEN REALTIME VALID

EP INFO:
INST_IP INST_PORT INST_OK INAME ISTATUS IMODE DSC_SEQNO DSC_CTL_NODE RTYPE RSTAT FSEQ FLSN CSEQ CLSN DW_STAT_FLAG
192.168.1.134 5236 OK SLNNGKBAK OPEN PRIMARY 0 0 REALTIME VALID 377386 426111 377386 426111 NONE

<<DATABASE GLOBAL INFO:>>
DW_IP MAL_DW_PORT WTIME WTYPE WCTLSTAT WSTATUS INAME INST_OK N_EP N_OK ISTATUS IMODE DSC_STATUS RTYPE RSTAT
192.168.1.135 52141 2022-07-26 09:42:30 GLOBAL VALID OPEN SLNNGK OK 1 1 OPEN STANDBY DSC_OPEN REALTIME VALID

EP INFO:
INST_IP INST_PORT INST_OK INAME ISTATUS IMODE DSC_SEQNO DSC_CTL_NODE RTYPE RSTAT FSEQ FLSN CSEQ CLSN DW_STAT_FLAG
192.168.1.135 5236 OK SLNNGK OPEN STANDBY 0 0 REALTIME VALID 377376 426110 377376 426110 NONE

DATABASE(SLNNGK) APPLY INFO FROM (SLNNGKBAK), REDOS_PARALLEL_NUM (1):
DSC_SEQNO[0], (RSEQ, SSEQ, KSEQ)[377385, 377385, 377386], (RLSN, SLSN, KLSN)[426110, 426110, 426111], N_TSK[0], TSK_MEM_USE[512]
REDO_LSN_ARR: (426110)