pxc集群中2个节点非正常关机，此时存活的节点变成 non-Primary

MariaDB [(none)]> show status like 'wsrep_cluster_status';
+----------------------+-------------+
| Variable_name | Value |
+----------------------+-------------+
| wsrep_cluster_status | non-Primary |
+----------------------+-------------+
1 row in set (0.001 sec)

MariaDB [(none)]> SET GLOBAL wsrep_provider_options='pc.bootstrap=true';
Query OK, 0 rows affected (0.004 sec)

MariaDB [(none)]> show status like 'wsrep_cluster_status';
+----------------------+---------+
| Variable_name | Value |
+----------------------+---------+
| wsrep_cluster_status | Primary |
+----------------------+---------+
1 row in set (0.001 sec)

MariaDB [(none)]> exit
Bye
[oracle@204_maridb mysql]$

确保其它集群关闭的情况下，使节点正常
SET GLOBAL wsrep_provider_options='pc.bootstrap=true';

其它节点执行
/usr/bin/mysqld_safe --wsrep-recover
根据错误日志获取掉线时的seqno
修改参数文件 grastates.dat
vi grastates.dat
--如果此seqno 大于存活节点的wsrep_local_cached_downto值，
--直接启动mysql服务
systemctl start mysql

注意：
A 节点存活，B节点加入后，C节点加入时需要指定A作为 sst的donor
在A节点执行 show global variables like '%node_name%';
mysqld_safe --wsrep_sst_donor=nodeA