Repair MBR (Master Boot Record) sector failure
cause of issue
Viruses, Trojans and other damage caused
Incorrect partitioning, disk read and write misuse
Symptom
To find a boot program, start interrupt
Unable to load the operating system, the boot black
Solutions
You should make a backup file in advance
RHEL installation CD to boot into emergency mode
Restore from a backup file
bak backup files
View Subdivision
disk partition
Format the partition
Establish mount point directory
Backup MBR sector data
Simulation of the fault is destroyed MBR
Exit CD
Reboot reboot
Linux CD-ROM boot into emergency mode
Reboot into emergency mode
Reply MBR sector from a backup file
Repair GRUB boot failure
cause of issue
GRUB boot loader in the MBR is destroyed
grub.conf file is missing, the boot configuration error
Symptom
System boot stagnation, display "grub>" prompt
Solutions
Try to manually enter the boot command
Enter emergency mode, return from a backup grub.conf
Grub program to rebuild MBR sector
Restore from a backup file
check the file
Once mounted to make a backup of grub.conf
Delete the file grub.conf
Restart
Into the firmware
Select CD-ROM guide shift + F10 to save and exit No.
Enter emergency mode
Reply grub.conf file to mount two partitions from the backup file
After rebooting select the fourth option from the local disk
Forget the root password
cause of issue
Forgotten root password
Symptom
You can not require root privileges management manipulation
If there is no other available account will not login
Solutions
Boot into single-user mode and reset passwords grub> kernel ... single or s or 1
Or go to the emergency mode and then reset the password
Boot into single-user mode and reset the password
In the guide screen twice press e
Selected sub-menu item 2
Press e
Option 2
Knock box
Input 1
Enter
Input b
Execute passwd command to change the root user password
Repair the file system
cause of issue
Non-normal shutdown, sudden power outages, equipment failures and other reading and writing
Super fast file system (super-block) information to be destroyed
Symptom
Unable to read or write data to the partition
After starting the prompt "Give root password for maintenance"
Solutions
Enter the repair status prompted, enter the root password
Use fsck command to repair
normal situation
Analog partition damage
检查是否能挂载该分区 报错 超级块信息被破坏
对分区/dev/sdb1进行修复 修复的时候文件系统不能处于挂载状态
重新挂载成功
磁盘资源耗尽故障
故障原因
磁盘空间已被大量的数据占满 空间耗尽
虽然还有可用空间 但文件数i节点耗尽
故障现象
无法写入新的文件 提示“… : 设备上没有空间”
部分程序无法运行 甚至系统无法启动
解决思路
清理磁盘空间 删除无用、冗余的文件
转移或删除占用大量i节点的琐碎文件
进入单用户模式、急救模式进行修复
为用户设置磁盘配额
查看磁盘空间和节点数
检测磁盘坏道
故障原因
磁盘设备中存在坏道(逻辑的或物理的)
故障现象
读取磁盘中的数据时，磁盘设备发出异常声响
访问磁盘中的某个文件，反复读取且出错，提示文件损坏
对于新建立的分区无法完成格式化
系统使用该磁盘时频繁死机
解决思路
检测硬盘中是否存在坏道
修复硬盘 或者更换新的硬盘
磁盘配额
实现磁盘配额的条件
需要Linux内核支持
安装quota软件包
Linux磁盘限额的特点
作用范围：针对指定的文件系统(分区)
限制对象：用户帐号、组帐号
限制类型：磁盘容量(默认单位为KB)文件数量
限制方法：软限制(可以越过七天)、硬限制(不能越过)
启用文件系统的配额支持 添加usrquota、grpquota挂载参数
重启
查看
创建配额文件 quotacheck
quotacheck -augcv
-a 检测所有可用的分区
-u 检测用户配额
-g 检测组配额
-c 创建配额数据文件
-v 显示执行过程信息
创建配额文件
需要临时关闭selinux
重新创建 报错是因为分区里面没有旧的配额文件
编辑用户和组账号的配额设置 edquota
创建一个新普通用户
编辑用户配额文件
启用、关闭文件系统的配额功能 quotaon、quotaoff
给backup挂载点目录开放权限 让用户对sdb1分区能进行操作
切换用户对分区进行写入
查看配额
使节点数超出配额 (touch命令创建的是0字节的文件)
再次查看配额 节点数也超出配额
查看配额使用情况 quota(侧重用户、组账号) rep相当于生成一个报表一样的东西
配额一般对root无效
