我试图将我的数据库移动到我的Ubuntu安装上的一个amazon EC2实例上的另一个安装，因为它填满了根目录。 我想我已经把事情搞砸了。 当我运行：
$ sudo mysqld --datadir=/var/lib/mysql --user mysql 110412 11:36:44 [Warning] Can't create test file /mnt/var/lib/mysql/ip-10-244-207-161.lower-test 110412 11:36:44 [Warning] Can't create test file /mnt/var/lib/mysql/ip-10-244-207-161.lower-test 在/var/log/mysql/error.log ：
110412 16:01:27 [Note] Plugin 'FEDERATED' is disabled. /usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13) 110412 16:01:27 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it. /usr/sbin/mysqld: Can't create/write to file '/mnt/tmp/ibRTnZix' (Errcode: 13) 110412 16:01:27 InnoDB: Error: unable to create temporary file; errno: 13 110412 16:01:27 [ERROR] Plugin 'InnoDB' init function returned error. 110412 16:01:27 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 110412 16:01:27 [ERROR] /usr/sbin/mysqld: Can't create/write to file '/mnt/var/lib/mysql/ip-10-244-207-161.pid' (Errcode: 13) 110412 16:01:27 [ERROR] Can't start server: can't create PID file: Permission denied
文件ip-10-244-207-161.lower-test尚不存在：
ls -l /mnt/var/lib/mysql total 20532 -rwxr-xr-x 1 mysql root 0 2011-02-28 22:23 debian-5.1.flag -rwxr-xr-x 1 mysql mysql 10485760 2011-04-12 07:31 ibdata1 -rwxr-xr-x 1 mysql mysql 5242880 2011-04-12 07:31 ib_logfile0 -rwxr-xr-x 1 mysql mysql 5242880 2011-02-28 22:23 ib_logfile1 drwxr-xr-x 2 mysql root 4096 2011-02-28 22:23 mysql -rwxr-xr-x 1 mysql root 6 2011-02-28 22:23 mysql_upgrade_info drwxr-xr-x 2 mysql mysql 4096 2011-04-11 08:22 scrapy_cache
目录似乎是可访问的：
$ ls -l /mnt/var/lib/ | grep mysql drwxr-xr-x 4 mysql mysql 4096 2011-04-12 07:31 mysql $ ls -l /var/lib/ | grep mysql lrwxrwxrwx 1 mysql root 18 2011-04-12 09:05 mysql -> /mnt/var/lib/mysql ls -ld /mnt/{,var/{,lib/{,mysql}}} drwxr-xr-x 5 root root 4096 2011-04-12 07:27 /mnt/ drwxr-xr-x 3 mysql root 4096 2011-04-12 07:29 /mnt/var/ drwxr-xr-x 3 mysql ubuntu 4096 2011-04-12 07:33 /mnt/var/lib/ drwxr-xr-x 4 mysql mysql 4096 2011-04-12 07:31 /mnt/var/lib/mysql
我在my.cnf中更改的部分：
user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /mnt/var/lib/mysql tmpdir = /mnt/tmp skip-external-locking
我真的很感激一些帮助，因为我试图debugging时失败了。
我做了一个sudo chown -R mysql /mnt/var/lib/mysql所以一切都应该由mysql服务器所有。 /mnt是肯定可写的，因为我在运行时运行了mv /var/lib/mysql /mnt/var/lib/ 。 Mount确认这一点：
$ mount | grep /mnt /dev/sda2 on /mnt type ext3 (rw)
磁盘没有满的空间，它没有用完inode，磁盘配额似乎没有活动我安装了repquota但它绝对没有输出：
$ df -h /dev/sda2 Filesystem Size Used Avail Use% Mounted on /dev/sda2 335G 2.0G 316G 1% /mnt $ df -i /dev/sda2 Filesystem Inodes IUsed IFree IUse% Mounted on /dev/sda2 44564480 104 44564376 1% /mnt
按照注释中的build议，创build与MySQL用户一样的东西：
$ su -s /bin/bash - mysql $ touch /mnt/var/lib/mysql/ip-10-244-207-161.lower-test $ ls -ld /mnt/var/lib/mysql/ip-10-244-207-161.lower-test -rw-r--r-- 1 mysql mysql 0 2011-04-12 14:10 /mnt/var/lib/mysql/ip-10-244-207-161.lower-test $ rm -f /mnt/var/lib/mysql/ip-10-244-207-161.lower-test $ ls -ld /mnt/var/lib/mysql/ip-10-244-207-161.lower-test ls: cannot access /mnt/var/lib/mysql/ip-10-244-207-161.lower-test: No such file or directory
MySql没有运行。
$ ps aux | grep mysql ubuntu 20825 0.0 0.0 3700 776 pts/1 S+ 15:40 0:00 grep --color=auto mysql
/etc/mysql/my.cnf
# # The MySQL database server configuration file. # # You can copy this to one of: # - "/etc/mysql/my.cnf" to set global options, # - "~/.my.cnf" to set user-specific options. # # One can use all long options that the program supports. # Run program with --help to get a list of available options and with # --print-defaults to see which it would actually understand and use. # # For explanations see # http://dev.mysql.com/doc/mysql/en/server-system-variables.html # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # # # * IMPORTANT # If you make changes to these settings and your system uses apparmor, you may # also need to also adjust /etc/apparmor.d/usr.sbin.mysqld. # user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /mnt/var/lib/mysql tmpdir = /mnt/tmp skip-external-locking # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. bind-address = 127.0.0.1 # # * Fine Tuning # key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched myisam-recover = BACKUP #max_connections = 100 #table_cache = 64 #thread_concurrency = 10 # # * Query Cache Configuration # query_cache_limit = 1M query_cache_size = 16M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. # As of 5.1 you can enable the log at runtime! #general_log_file = /var/log/mysql/mysql.log #general_log = 1 log_error = /var/log/mysql/error.log # Here you can see queries with especially long duration #log_slow_queries = /var/log/mysql/mysql-slow.log #long_query_time = 2 #log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 16M # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/
我终于明白了问题所在。 我有ec2实例运行（默认安装） apparmor 。 为了停止抱怨，我做了：
sudo aa-complain /usr/sbin/mysqld
现在MySQL开始像预期的，我可以查询我的数据。 我为这样一个微不足道的问题花了这么多时间感到很难过，我真的很感激每个人都有帮助。 如果没有用户询问关于selinux的问题，我就不会想出问题了。
另一种解决scheme可以是configurationapparmor来允许你使用这些目录（我不在乎），这在我发现的博客文章中有描述。
文件/mnt/var/lib/mysql/ip-10-244-207-161.lower-test是否存在？ 如果是，它是由mysql拥有的？ /mnt/var/lib/mysql目录中的所有文件应该由MySQL用户拥有。
/mnt挂载为rw （读写），而不是ro （只读）？ 你可以通过运行mount （不带参数）来检查。
MySQL在这个错误的文档中有一个页面 。 这基本上意味着数据目录或文件系统是写保护的。
磁盘配额是否有效？ 您可以检查当前的配额状态（如果已安装）：
sudo repquote -a
磁盘已满？ 检查当前的磁盘使用情况：
df -h
它闻起来像问题可能是由于/mnt/var/lib/mysql的父目录的权限不足，特别是可能是/mnt/var 。 你可以发布ls -ld /mnt/{,var/{,lib/{,mysql}}}吗？
编辑：好吧，想一想更多。 你说你在my.cnf改变了套接字的位置 – 可能是服务器启动成功（用ps ax | grep mysql检查），但是你正在使用的mysql 客户端正在寻找其他地方的套接字，比如一个老的位置？ 从运行mysql得到的完整错误信息是什么？
检查SELinux。 如果SELinux处于打开状态，则需要重新标记或closuresSELinux。 这会给出一个权限错误信息。
你有错误的数据目录？
你写了：
$ sudo mysqld --datadir=/var/lib/mysql --user mysql
但应该是：
$ sudo mysqld --datadir=/mnt/var/lib/mysql --user mysql