将 MySQL 数据库复制到另一台机器
我正在尝试在另一台服务器上创建 MySQL 数据库的副本。我停止服务器，压缩 mysql 目录，将其复制到另一台服务器并解压缩。我设置了所有权限以匹配工作服务器，并复制了 my.cnf 文件，因此除了服务器特定的更改之外，一切都是相同的。
但是，当我尝试启动服务器时，出现以下 InnoDB 错误：
InnoDB: Operating system error number 13 in a file operation.
This error means mysql does not have the access rights to
the directory.
File name /var/lib/mysql/ibdata1
File operation call: 'open'.
所有文件的所有者/组是 mysql。我什至尝试将权限更改为a+rw。我可以 su 到 mysql 用户并使用 head 访问 ibdata1 文件。
解决方案：
问题是启用了selinux，导致新文件无法被访问。
I'm trying make a copy of a MySQL database on another server. I stop the server, tar up the mysql directory, copy it to the other server and untar it. I set all the permissions to match to the working server, and copied the my.cnf file so everything is the same except for server specific changes.
However, when I try to startup the server, I get the following InnoDB error:
InnoDB: Operating system error number 13 in a file operation.
This error means mysql does not have the access rights to
the directory.
File name /var/lib/mysql/ibdata1
File operation call: 'open'.
The owner/group for all the files is mysql. I even tried changing permissions to a+rw. I can su to the mysql user and access the ibdata1 file using head.
SOLUTION:
The problem was selinux was enabled and preventing the new files from being accessed.
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一个愚蠢的问题，但人们忘记了：你说你检查了所有文件是否具有相同的权限；尽管如此，即使消息中这么说，您是否可能忘记检查包含目录的权限？？
更新：另外两个建议：
您可以尝试插入
--console和--log-warnings标志，以获得大量调试输出，像这样（在我的 Mac 上）：/usr/libexec/mysqld --console --log-warnings --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld /mysqld.pid --skip-external-locking --socket=/var/lib/mysql/mysql.sock
如果全部否则失败，您可以尝试 strace mysqld ... 来看看它到底失败了。错误将出现在底部的某个地方。
更新2：确实有趣......我看不到你的操作系统是什么。我通常不使用
/sbin/service，它对我来说有点神秘；在 Mac 上，它已被弃用，取而代之的是launchctl以及/System/Library/LaunchDaemons/mysqld.plist中的配置文件，并且在大多数 Linux 机器上，您都有/ etc/init.d/mysqld。所以你可以在那里插入 strace 。或者（未经测试，但联机帮助页表明这是可能的）您可以尝试跟踪服务调用：
这应该会生成文件
straces.pid，其中之一应该是 mysqld 的，希望您能在那里找到错误。A silly question, but people forget: you said you checked that all files have the same permissions; still, even though it said so in the message, might you possibly have forgotten to check the permissions on the containing directory?
UPDATE: Two more suggestions:
You might try inserting
--consoleand--log-warningsflags, for lots of debugging output, something like this (on my Mac):/usr/libexec/mysqld --console --log-warnings --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-external-locking --socket=/var/lib/mysql/mysql.sock
If all else fails, you can probably try
strace mysqld ...to see what exactly is it failing. The error will be somewhere at the bottom.UPDATE2: Interesting indeed... I can't see what your OS is. I normally don't use
/sbin/service, it's a bit mysterious for me; on a Mac, it's deprecated in favour oflaunchctlwith config file in/System/Library/LaunchDaemons/mysqld.plist, and on most Linux boxes you have/etc/init.d/mysqld. So you could insert strace there.Or (untested, but manpage suggests it's possible) you could try stracing the service call:
This should produce files
straces.pid, one of which should be mysqld's, and hopefully you'll find your error there.这不是对您的问题的直接答案，但我建议您尝试使用这些程序之一来满足您的备份/恢复需求。
Percona Xtrabackup：https://launchpad.net/percona-xtrabackup
Mydumper： http://www.mydumper.org/
两者都是很棒的工具，都是免费和开源的，并且将帮助您完全避免这个问题。
希望有帮助。
This isn't a direct answer to your question, but I would recommend trying one of these programs for your backup / restore needs.
Percona Xtrabackup: https://launchpad.net/percona-xtrabackup
Mydumper: http://www.mydumper.org/
Both are great tools, are free and open source, and will help you avoid that problem entirely.
Hope that helps.