mysql - 移动Mysql数据目录

Question

我在将 mysql 数据目录移动到新位置时遇到问题。我正在运行 Linux Mint 17、MySQL 5.7.19。我已经在这两个位置尝试了说明:

How to change MySQL data directory?

这个答案: https://stackoverflow.com/a/10209282/7850358

和本指南: https://www.digitalocean.com/community/tutorials/how-to-move-a-mysql-data-directory-to-a-new-location-on-ubuntu-16-04

我相信我遇到了与这个问题类似的问题:https://dba.stackexchange.com/questions/101732/how-do-i-move-a-mysql-data-directory-to-an-external-hard-drive

我将数据从 /var/lib/mysql rsync 到 /media/mike/DataBase。该目录存在，并在 /etc/mysql/mysql.conf.d/mysqld.cnf 中正确指定，我在 /etc/apparmor.d/tunables/中创建了一个别名别名。我确保文件夹的权限正确:drwx------ 11 mysql mysql 4096 Jan 21 16:52 mysql。

我重新启动 apparmor，没问题。我重新启动 mysql 服务器 - 我得到这个:

Thudbucket mike # sudo systemctl start mysql
Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
Thudbucket mike # systemctl status mysql.service
● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
   Active: activating (start-post) (Result: exit-code) since Sun 2018-01-21 17:10:34 EST; 12s ago
  Process: 22295 ExecStart=/usr/sbin/mysqld (code=exited, status=1/FAILURE)
  Process: 22288 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 22295 (code=exited, status=1/FAILURE);         : 22296 (mysql-systemd-s)
   CGroup: /system.slice/mysql.service
           └─control
             ├─22296 /bin/bash /usr/share/mysql/mysql-systemd-start post
             └─22332 sleep 1

Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.308875Z 0 [Warning] Changed limits: max_open_files: 1024 (requested 5000)
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.308930Z 0 [Warning] Changed limits: table_open_cache: 431 (requested 2000)
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.453972Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server opti
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.454033Z 0 [Warning] Can't create test file /media/mike/DataBase/mysql/Thudbucket.lower-test
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.454054Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.19-0ubuntu0.16.04.1) starting as process 22295 ...
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.455725Z 0 [Warning] Can't create test file /media/mike/DataBase/mysql/Thudbucket.lower-test
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.455735Z 0 [Warning] Can't create test file /media/mike/DataBase/mysql/Thudbucket.lower-test
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.455760Z 0 [ERROR] failed to set datadir to /media/mike/DataBase/mysql/
Jan 21 17:10:34 Thudbucket mysqld[22295]: 2018-01-21T22:10:34.455774Z 0 [ERROR] Aborting
Jan 21 17:10:34 Thudbucket systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE

Answer 1

我已经尝试了几乎所有我能在网上找到的东西。我什至阅读了手册，以进行更改。出于某种原因，将数据目录移动到除/var/lib/mysql 之外的任何位置都会导致错误。

我最终在这次黑客攻击中运气更好: https://askubuntu.com/a/663945/785778

## copy with permissions intact:
rsync -avzh /var/lib/mysql /path/to/new/place

## back up original
mv /var/lib/mysql /var/lib/_mysql 

## create a new empty directory in place of old:
mkdir /var/lib/mysql 

## bind mount the new location to the old:
mount -B /path/to/new/place /var/lib/mysql

重启mysql后一切正常

具有讽刺意味的是 - 符号链接(symbolic link)没有工作

编辑

这似乎是一个错误，但提供的解决方案并没有为我解决问题:

https://bugs.launchpad.net/ubuntu/+source/mysql-5.7/+bug/1574782 https://forums.mysql.com/read.php?11,653198,653198#msg-653198

该错误的工作原理如下:MySQL 在启动时查找是否存在 /var/lib/mysql/ 和 /var/lib/mysql/mysql 目录。提供的解决方案是保留 /var/lib/mysql 和 /var/lib/mysql/mysql 目录，但删除内容并将新的 datadir 路径添加到 apparmor 配置文件 (/etc/apparmor.d/usr.sbin.mysqld) 并重新加载它 (/etc/init.d/apparmor reload)。

但重复一遍，虽然我遇到了同样的问题(MySQL 一直在 /var/lib/mysql 寻找数据目录)，但唯一对我有用的解决方案是挂载数据目录位于 /var/lib/mysql/。