OS: Cent OS 6.3
DB: 5.5.14
看到一个帖子，在服务器上安装了oracle和mysql数据库，mysql数据库忘记开启innodb_file_per_table，导致插入测试数据后磁盘空间爆满，mysql启动报错，并且无法启动。
1、可以直接删除ibdata文件后重建mysql数据库，but，里面还有一些有用数据，因此无法直接删除ibdata进行操作，只能另谋出路。
2、Linux默认会保留5%的空间，用tune2fs命令
模拟：
服务器上也有oracle和mysql数据库，用dd直接把磁盘空间撑爆
dd if=/dev/zero of=/export/test bs=50MB count=2000
[root@db01 export]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
50G 48G 0 100% /
tmpfs 7.7G 0 7.7G 0% /dev/shm
/dev/sda1 485M 32M 429M 7% /boot
[root@db01 ~]# service mysqld stop
Shutting down MySQL............................................ SUCCESS!
[root@db01 ~]# service mysqld start
Starting MySQL.................................................................................................................................................................................................................................................................................................................................无法正常启动
数据库忘记设置innodb_fiile_per_table，其它库中又有有用数据，无法直接删除ibdata重新配置
在Linux系统中，默认会保留5%的空间
[root@db01 log]# tune2fs -m 1 /dev/mapper/VolGroup-lv_root
tune2fs 1.41.12 (17-May-2010)
Setting reserved blocks percentage to 1% (131072 blocks)
查看磁盘空间：
[root@db01 log]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
50G 48G 783M 99% /
tmpfs 7.7G 0 7.7G 0% /dev/shm
/dev/sda1 485M 32M 429M 7% /boot
空间由原来的100%变成了99%，尝试启动mysql数据库
[root@db01 ~]# service mysqld start
Starting MySQL SUCCESS!
[root@db01 ~]# ps -ef | grep mysql
root 31405 1 3 00:37 pts/2 00:00:00 /bin/sh /export/servers/mysql/bin/mysqld_safe --datadir=/export/servers/mysql/data --pid-file=/export/servers/mysql/tmp/mysql.pid
mysql 32200 31405 63 00:37 pts/2 00:00:01 /export/servers/mysql/bin/mysqld --basedir=/export/servers/mysql --datadir=/export/servers/mysql/data --plugin-dir=/export/servers/mysql/lib/plugin --user=mysql --log-error=/export/servers/mysql/log/error.log --open-files-limit=65535 --pid-file=/export/servers/mysql/tmp/mysql.pid --socket=/export/servers/mysql/tmp/mysql.sock --port=3306
root 32218 27979 0 00:37 pts/2 00:00:00 grep mysql
[root@db01 bin]# ./mysql -uroot -S /export/servers/mysql/tmp/mysql.sock
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.14-log Source distribution
Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sakila |
| test |
| yoon |
+--------------------+
6 rows in set (0.05 sec)
mysql>
最后通过mysqldump备份数据库，删除ibdata重新配置mysql，并设置innodb_file_per_table 为 on
tune2fs用法：
1、tune2fs --help
2、找度娘