xtrabackup 备份 MySQL 8.0.20 时报错：
200626 08:40:59 Connecting to MySQL server host: localhost, user: root, password: set, port: 3306, socket: /data/mysql/mysql3306/tmp/mysql3306.sock
xtrabackup: Redo Log Archiving is not set up.
Unknown redo log format (4). Please follow the instructions at http://dev.mysql.com/doc/refman/8.0/en/ upgrading-downgrading.html.
xtrabackup: Error: recv_find_max_checkpoint() failed.
原是，当前版本的 xtrabackup 不支持 MySQL 8.0.20 需要升级 xtrbackup 到8.0.13即可。
xtrabackup --defaults-file=/data/mysql/mysql3306/my3306.cnf -S /data/mysql/mysql3306/tmp/mysql3306.sock -uroot --no-timestamp --backup --target-dir /data/backup/db3306_`date +%Y%m%d` -p
输入密码。搞定。