PXC 5.7 WSREP_SST: [ERROR] xtrabackup_checkpoints missing
PXC5.7，在启动其中的一个节点，碰到了 [ERROR] xtrabackup_checkpoints missing. xtrabackup/SST failed on DONOR。关于这个错误，需要从其它节点来获取更详细的日志描述。下文是对这个问题的描述及解决，供大家参考。
查看mysql的error日志
2019-11-18T01:20:26.272600Z WSREP_SST: [INFO] ............Waiting for SST streaming to complete!
2019-11-18T01:20:36.337188Z WSREP_SST: [ERROR] ******************* FATAL ERROR ******************
2019-11-18T01:20:36.339656Z WSREP_SST: [ERROR] xtrabackup_checkpoints missing. xtrabackup/SST failed on DONOR. Check DONOR log
2019-11-18T01:20:36.341983Z WSREP_SST: [ERROR] ******************************************************
2019-11-18T01:20:36.344763Z WSREP_SST: [ERROR] Cleanup after exit with status:2
2019-11-18T01:20:36.361115Z 0 [ERROR] WSREP: Process completed with error: wsrep_sst_xtrabackup-v2 --role 'joiner' --address '172.27.1.243' --datadir '/var/lib/mysql/' --defaults-file '/etc/my.cnf' --defaults-group-suffix '' --parent '16265' '' : 2 (No such file or directory)
2019-11-18T01:20:36.361205Z 0 [ERROR] WSREP: Failed to read uuid:seqno from joiner script.
2019-11-18T01:20:36.361222Z 0 [ERROR] WSREP: SST script aborted with error 2 (No such file or directory)
2019-11-18T01:20:36.361662Z 0 [ERROR] WSREP: SST failed: 2 (No such file or directory)
2019-11-18T01:20:36.361722Z 0 [ERROR] Aborting
查看主节点/var/lib/mysql/innobackup.backup.log
xtrabackup: recognized server arguments: --datadir=/var/lib/mysql --log_bin --server-id=1 --defaults_group=mysqld --parallel=4
xtrabackup: recognized client arguments: --socket=/var/lib/mysql/mysql.sock --user=admin --password=* --socket=/var/lib/mysql/mysql.sock --lock-ddl=1 --backup=1 --galera-info=1 --binlog-info=ON --stream=xbstrea
m --target-dir=/tmp/pxc_sst_tApK/donor_xb_JGrT
191118 09:19:36 version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup;mysql_socket=/var/lib/mysql/mysql.sock' as 'admin' (using password: YES).
Failed to connect to MySQL server: DBI connect(';mysql_read_default_group=xtrabackup;mysql_socket=/var/lib/mysql/mysql.sock','admin',...) failed: Access denied for user 'admin'@'localhost' (using password: YES)
at - line 1314.
191118 09:19:36 Connecting to MySQL server host: localhost, user: admin, password: set, port: not set, socket: /var/lib/mysql/mysql.sock
Failed to connect to MySQL server: Access denied for user 'admin'@'localhost' (using password: YES).
从上面的错误可知，用于SST同步的用户访问被拒绝，测试SST用户能否登陆，经测试，确实无法登陆
解决方法：
主节点执行
mysql> alter user 'admin'@'localhost' identified by 'pxcpasswor'; --为账户修改密码
Query OK, 0 rows affected (0.05 sec)、
重启本节点mysql即可