升级 MySQL 8.0.30 之前请注意备份，Dynamic Redo log Sizing影响了 Xtrabackup！

MySQL 8.0.30于2022年7月26日发布，它有一个很好的功能列表。

• 生成的不可见主键
• 动态重做日志大小
• 监控组复制内存的工具
• 支持 Ubuntu 22.04

对于数据库管理员和数据库可靠性工程师来说，最显着的特性是动态重做日志记录。

更广泛采用的开源备份工具是 Xtrabackup。重做日志设计的变化影响了这个热备份工具。

2022-10-04T18:40:08.211998+05:30 0 [Note] [MY-011825] [Xtrabackup] recognized server arguments: --datadir=/var/lib/mysql 
2022-10-04T18:40:08.212264+05:30 0 [Note] [MY-011825] [Xtrabackup] recognized client arguments: --user=root --password=* --user=sysbench --password=* --backup=1 --target-dir=/root/backup --no-server-version-check=1 
xtrabackup version 8.0.29-22 based on MySQL server 8.0.29 Linux (x86_64) (revision id: c31e7ddcce3)
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LC_CTYPE = "UTF-8",
	LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
220908 18:40:08  version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup' as 'sysbench'  (using password: YES).
220908 18:40:08  version_check Connected to MySQL server
220908 18:40:08  version_check Executing a version check against the server...
220908 18:40:08  version_check Done.
2022-10-04T18:40:08.322073+05:30 0 [Note] [MY-011825] [Xtrabackup] Connecting to MySQL server host: localhost, user: sysbench, password: set, port: not set, socket: not set
2022-10-04T18:40:08.330837+05:30 0 [Note] [MY-011825] [Xtrabackup] Using server version 8.0.30
2022-10-04T18:40:08.334162+05:30 0 [Note] [MY-011825] [Xtrabackup] Executing LOCK INSTANCE FOR BACKUP ...
2022-10-04T18:40:08.336817+05:30 0 [Note] [MY-011825] [Xtrabackup] uses posix_fadvise().
2022-10-04T18:40:08.336864+05:30 0 [Note] [MY-011825] [Xtrabackup] cd to /var/lib/mysql
2022-10-04T18:40:08.336886+05:30 0 [Note] [MY-011825] [Xtrabackup] open files limit requested 0, set to 1024
2022-10-04T18:40:08.337255+05:30 0 [Note] [MY-011825] [Xtrabackup] using the following InnoDB configuration:
2022-10-04T18:40:08.337266+05:30 0 [Note] [MY-011825] [Xtrabackup] innodb_data_home_dir = .
2022-10-04T18:40:08.337274+05:30 0 [Note] [MY-011825] [Xtrabackup] innodb_data_file_path = ibdata1:12M:autoextend
2022-10-04T18:40:08.337314+05:30 0 [Note] [MY-011825] [Xtrabackup] innodb_log_group_home_dir = ./
2022-10-04T18:40:08.337322+05:30 0 [Note] [MY-011825] [Xtrabackup] innodb_log_files_in_group = 2
2022-10-04T18:40:08.337333+05:30 0 [Note] [MY-011825] [Xtrabackup] innodb_log_file_size = 50331648
2022-10-04T18:40:08.337941+05:30 0 [Note] [MY-013251] [InnoDB] Number of pools: 1
2022-10-04T18:40:08.339067+05:30 0 [Note] [MY-011825] [Xtrabackup] inititialize_service_handles suceeded
2022-10-04T18:40:08.515699+05:30 0 [ERROR] [MY-012592] [InnoDB] Operating system error number 2 in a file operation.
2022-10-04T18:40:08.515754+05:30 0 [ERROR] [MY-012593] [InnoDB] The error means the system cannot find the path specified.
2022-10-04T18:40:08.515766+05:30 0 [ERROR] [MY-012594] [InnoDB] If you are installing InnoDB, remember that you must create directories yourself, InnoDB does not create them.
2022-10-04T18:40:08.515778+05:30 0 [ERROR] [MY-012646] [InnoDB] File ./ib_logfile0: 'open' returned OS error 71. Cannot continue operation
2022-10-04T18:40:08.515795+05:30 0 [ERROR] [MY-012981] [InnoDB] Cannot continue operation.

备份将失败并显示错误代码

“2022-10-04T18:40:08.515778+05:30 0 [ERROR] [MY-012646] [InnoDB] File ./ib_logfile0: ‘open’ returned OS error 71. Cannot continue operation”

Xtrabackup 正在寻找ib_logfile 0 ，新设计（8.0.30）没有 ib_logfile0。

MySQL 8.0.20中的重做日志格式更改影响了以前版本的 Xtrabackup。8.0.20重做日志格式改变的原因

• InnoDB： 由于撤消表空间 ID 值的更改，在 MySQL 8.0 中修改撤消表空间的重做日志记录的大小增加了，这需要额外的字节。重做日志记录大小的变化导致具有大量写入 I/O 的工作负载的性能下降。为了解决这个问题，修改了重做日志格式以减少修改撤消表空间的重做日志记录大小。(Bug #29536710)

https://forums.percona.com/t/mysql-8-0-20-support/7584/2

发布此更改 Xtrabackup 已使 Xtrabackup 版本与源 MySQL 版本匹配。因此默认情况下，Xtrabackup 在备份初始化之前验证 MySQL 版本。引入了一个新变量–no-server-version-check来禁用版本检查。

https://docs.percona.com/percona-xtrabackup/8.0/using_xtrabackup/comparison.html

关键要点：

由于 MySQL 8.0 次要版本升级是一种选择。在生产中升级 MySQL 次要版本之前，请对备份工具进行重要检查。

原文标题：Beware of your Backup before upgrading MySQL 8.0.30

原文作者：mahaganapathineedi

原文链接：https://mydbops.wordpress.com/2022/10/13/beware-of-your-backup-before-upgrading-mysql-8-0-30/