Assuming that a node of three node Mgr is abnormal, you need to add this node to the Mgr cluster again. The specific operation process is as follows:
Contributor side execution (192.168.1.11)
DROP USER 'donor_clone_user'@'192.168.1.12';
CREATE USER 'donor_clone_user'@'192.168.1.12' IDENTIFIED BY 'password';
GRANT BACKUP_ADMIN on *.* to 'donor_clone_user'@'192.168.1.12';
INSTALL PLUGIN clone SONAME 'mysql_clone.so';
Receiver side execution（ 192.168.1.12 )
DROP USER 'recipient_clone_user'@'192.168.1.12';
CREATE USER 'recipient_clone_user'@'192.168.1.12' IDENTIFIED BY 'password';
GRANT CLONE_ADMIN on *.* to 'recipient_clone_user'@'192.168.1.12';
INSTALL PLUGIN clone SONAME 'mysql_clone.so';
SET GLOBAL clone_valid_donor_list = '192.168.1.11:3311';
exit
mysql -urecipient_clone_user -ppassword -h 192.168.1.12 -P3311
CLONE INSTANCE FROM 'donor_clone_user'@'192.168.1.11':3311 IDENTIFIED BY 'password';
exit
mysql -uroot -p
start group_replication;
select * from performance_schema.replication_group_members;
The above is the whole content of this article. I hope it will help you in your study, and I hope you can support developepaer more.