1：masterha_check_repl 副本集方面报错 replicates is not defined in the configuration file!
具体信息如下：
# /usr/local/bin/masterha_check_repl --conf=/etc/mha/app1.cnf
Thu Nov 21 15:33:15 2018 - [warning] Global configuration file /etc/masterha_default.cnf not found. Skipping. Thu Nov 21 15:33:15 2018 - [info] Reading application default configuration from /etc/mha/app1.cnf.. Thu Nov 21 15:33:15 2018 - [info] Reading server configuration from /etc/mha/app1.cnf.. Thu Nov 21 15:33:15 2018 - [info] MHA::MasterMonitor version 0.56. Thu Nov 21 15:33:16 2018- [error][/usr/local/share/perl5/MHA/ServerManager.pm, ln671] Master 179.179.19.179:3306 from which slave 179.179.19.180(179.179.19.180:3306) replicates is not defined in the configuration file! Thu Nov 21 15:33:16 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. at /usr/local/share/perl5/MHA/MasterMonitor.pm line 326. Thu Nov 21 15:33:16 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers. Thu Nov 21 15:33:16 2018 - [info] Got exit code 1 (Not master dead). MySQL Replication Health is NOT OK!
分析：MHA 漂移过后，我们知道配置信息中 主节点的信息就不在了，我们需要及时维护，否则/usr/local/bin/masterha_check_repl --conf=/etc/mha/XXX.cnf 检查副本集状态报错。
2. masterha_master_switch 在线切换方面 报错 We should not start online master switch when one of connections are running long updates on the current master
具体信息如下：
# /usr/local/bin/masterha_master_switch --master_state=alive --conf=/etc/mha/app1.cnf It is better to execute FLUSH NO_WRITE_TO_BINLOG TABLES on the master before switching. Is it ok to execute on 179.179.19.184(179.179.19.184:3306)? (YES/no): y Tue Nov 19 17:19:09 2018 - [info] Executing FLUSH NO_WRITE_TO_BINLOG TABLES. This may take long time.. Tue Nov 19 17:19:09 2018 - [info] ok. Tue Nov 19 17:19:09 2018 - [info] Checking MHA is not monitoring or doing failover.. Tue Nov 19 17:19:09 2018 - [info] Checking replication health on 179.179.19.185.. Tue Nov 19 17:19:09 2018 - [info] ok. Tue Nov 19 17:19:09 2018 - [error][/usr/local/share/perl5/MHA/MasterRotate.pm, ln161] We should not start online master switch when one of connections are running long updates on the current master(179.179.19.184(179.179.19.184:3306)). Currently 1 update thread(s) are running. Details: {'Time' => '12815','db' => undef,'Id' => '1','User' => 'event_scheduler','State' => 'Waiting on empty queue','Command' => 'Daemon','Info' => undef,'Host' => 'localhost'} Tue Nov 19 17:19:09 2018 - [error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln177] Got ERROR: at /usr/local/bin/masterha_master_switch line 53.
分析：set global event_scheduler=off; 主从都要关闭
3. masterha_master_switch 在线切换方面 报错 Got Error: DBI .....failed: Access denied for user
# /usr/local/bin/masterha_master_switch --master_state=alive --conf=/etc/mha/app1.cnf Starting master switch from 179.179.19.185(179.179.19:3306) to 179.179.19.184(179.179.19.184:3306)? (yes/NO): yes Tue Nov 19 18:52:04 2018 - [info] Checking whether 179.179.19.184(179.179.19.184:3306) is ok for the new master.. Tue Nov 19 18:52:04 2018 - [info] ok. Tue Nov 19 18:52:04 2018 - [info] ** Phase 1: Configuration Check Phase completed. Tue Nov 19 18:52:04 2018 - [info] Tue Nov 19 18:52:04 2018 - [info] * Phase 2: Rejecting updates Phase.. Tue Nov 19 18:52:04 2018 - [info] Tue Nov 19 18:52:04 2018 - [info] Executing master ip online change script to disable write on the current master: Tue Nov 19 18:52:04 2018 - [info] /usr/local/bin/master_ip_online_change_appuanalysis --command=stop --orig_master_host=179.179.19.185 --orig_master_ip=179.179.19.185 --orig_master_port=3306--orig_master_user='weixinLX391P_xldbmha' --orig_master_password='weixinLX391P_xldbmha)qlk' --new_master_host=179.179.19.184 --new_master_ip=179.179.19.184 --new_master_port=55988 --new_master_user='us_mha' --new_master_password='weixinLX391P_xldbmha)qlk' --orig_master_ssh_user=root --new_master_ssh_user=root Got Error: DBI connect(';host=179.179.19.184;port=3306;mysql_connect_timeout=4','weixinLX391P_xldbmha',...) failed: Access denied for user 'weixinLX391P_xldbmha'@'179.179.19.166' (using password: YES) at /usr/local/share/perl5/MHA/DBHelper.pm line 205. at /usr/local/bin/master_ip_online_change_app1 line 119. Tue Nov 19 18:52:04 2018 - [error][/usr/local/share/perl5/MHA/ManagerUtil.pm, ln177] Got ERROR: at /usr/local/bin/masterha_master_switch line 53.
分析：账号密码有需要转移字符的。app1.cnf 文件中user账号相应的密码 password 不能有待转移的字符，例如本例中的')'，但是 账号 repl_user 相应的密码repl_password 没有此限制。
4.如果使用的是xtrabackup，注意从节点会把event还原上去，可能会造成数据不一致，同步失败的问题。
如果主节点有event，需要手动关闭从节点的event。例如，主节点有归档删除数据的event，从节点需要关闭，否则报错。类似如下错误：
Could not execute Delete_rows event on table ????DB.*****table; Can't find record in '*****', Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND; the event's master log FIRST, end_log_pos XXXXXXX