如何使用只读数据目录启动mysqld？

Question

我正在尝试使用主机挂载只读的数据目录在码头容器中启动MariaDB。MySQLd当然会关闭主机。不幸的是，即使将read_only标志添加到my.conf中，也会出现以下错误：

root@2380610236d1:/# mysqld --innodb-read-only
140807 19:19:38 [Warning] Can't create test file /var/lib/mysql/2380610236d1.lower-test
140807 19:19:38 [ERROR] mysqld: Can't create/write to file '/var/lib/mysql/aria_log_control' (Errcode: 13 "Permission denied")
140807 19:19:38 [ERROR] mysqld: Got error 'Can't create file' when trying to use aria control file '/var/lib/mysql/aria_log_control'
140807 19:19:38 [ERROR] Plugin 'Aria' init function returned error.
140807 19:19:38 [ERROR] Plugin 'Aria' registration as a STORAGE ENGINE failed.
140807 19:19:38 [Note] InnoDB: Started in read only mode
140807 19:19:38 [Note] InnoDB: Using mutexes to ref count buffer pool pages
140807 19:19:38 [Note] InnoDB: The InnoDB memory heap is disabled
140807 19:19:38 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
140807 19:19:38 [Note] InnoDB: Compressed tables use zlib 1.2.8
140807 19:19:38 [Note] InnoDB: Using Linux native AIO
140807 19:19:38 [Note] InnoDB: Using CPU crc32 instructions
140807 19:19:38 [Note] InnoDB: Disabling background IO write threads.
140807 19:19:38 [Warning] InnoDB: Unable to open "./ib_logfile0" to check native AIO read support.
140807 19:19:38 [Warning] InnoDB: Linux Native AIO disabled.
140807 19:19:38 [Note] InnoDB: Initializing buffer pool, size = 256.0M
140807 19:19:38 [Note] InnoDB: Completed initialization of buffer pool
2014-08-07 19:19:38 7f2bc5a247c0  InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.
140807 19:19:38 [ERROR] InnoDB: os_file_get_status() failed on './ibdata1'. Can't determine file permissions
140807 19:19:38 [ERROR] InnoDB: The system tablespace must be writable!
140807 19:19:38 [ERROR] Plugin 'InnoDB' init function returned error.
140807 19:19:38 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
140807 19:19:38 [Note] Plugin 'FEEDBACK' is disabled.
140807 19:19:38 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
Couldn't start tokudb because some other tokudb process is using the same directory [/var/lib/mysql/] for [environment]
140807 19:19:38 [ERROR] Plugin 'TokuDB' init function returned error.
140807 19:19:38 [ERROR] Plugin 'TokuDB' registration as a STORAGE ENGINE failed.
140807 19:19:38 [ERROR] Unknown/unsupported storage engine: InnoDB
140807 19:19:38 [ERROR] Aborting

140807 19:19:38 [Note] mysqld: Shutdown complete

如何使用只读数据目录启动数据库服务器？

Answer 1

请注意InnoDB体系结构(由Percona CTO Vadim Tkachenko表示)

系统表空间文件ibdata1有需要写入的移动部件。

• 数据字典
• 双写缓冲器
  • 防止资料贪污的安全网
  • 帮助Bypass OS缓存

• 插入缓冲区(流线更改为辅助索引)
• 回滚段
• 撤消日志

-无害-只读设置为InnoDB处理只读情况是件好事。

您还需要确保诺姆b_变化_缓冲为0。

你还需要确保崩溃的恢复永远不会发生。这里是如何设置它。

首先，使用可写媒体上的数据库，登录到MySQL并运行如下：

mysql> set global innodb_fast_shutdown = 0;

然后，转到操作系统并运行

service mysql stop

启用诺姆b后，这将导致mysqld在关闭InnoDB管道时将所有设备及其祖母从InnoDB管道中清除出来。

接下来，将datadir移动到只读媒体。

然后，将其添加到my.conf中

[mysqld]
innodb_change_buffering = 0
innodb_read_only = 1

最后，使用service mysql start和InnoDB启动mysql应该非常快，因为没有必要执行崩溃恢复，因为所有东西都是事先从InnoDB管道中清除出来的。