Linux磁盘空间爆满，MySQL无法启动

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