磁盘、LVM和文件系统

一、磁盘及分区

1.检测并确认新硬盘

# fdisk -l

 

Disk /dev/sda:21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0x00078511

 

  Device Boot      Start         End      Blocks  Id  System

/dev/sda1  *           1          64      512000  83  Linux

Partition 1 does not end on cylinderboundary.

/dev/sda2              64        2611   20458496   8e  Linux LVM

 

Disk /dev/sdb:21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0x00000000

 

 

Disk /dev/sdc:26.8 GB, 26843545600 bytes

255 heads, 63 sectors/track, 3263 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0x00000000

 

2.规划硬盘中的分区

# fdisk /dev/sdb

Device contains neither a valid DOSpartition table, nor Sun, SGI or OSF disklabel

Building a new DOS disklabel with diskidentifier 0xae03f6ac.

Changes will remain in memory only, untilyou decide to write them.

After that, of course, the previous contentwon't be recoverable.

 

Warning:invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

 

WARNING:DOS-compatible mode is deprecated. It's strongly recommended to

        switch off the mode (command 'c') and change display units to

        sectors (command 'u').

 

Command (m forhelp): p         ←查看分区信息，看是否创建过分区，以免重复

 

Disk /dev/sdb:21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0xae03f6ac

 

  Device Boot      Start         End      Blocks  Id  System

 

Command (m forhelp): n         ←新建分区

Command action

  e   extended

  p   primary partition (1-4)

p                              ←选择主分区

Partition number (1-4): 1      ←选择分区号

First cylinder (1-2610, default 1):

Using defaultvalue 1

Last cylinder, +cylinders or +size{K,M,G}(1-2610, default 2610): +100M     ←分区的大小

 

Command (m forhelp): p         ←查看是否创建成功

 

Disk /dev/sdb:21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0xae03f6ac

 

  Device Boot      Start         End      Blocks  Id  System

/dev/sdb1               1          14      112423+ 83  Linux

 

Command (m forhelp): w          ←保存并退出

The partition table has been altered!

 

Calling ioctl() to re-read partition table.

Syncing disks.

 

3.删除分区

# fdisk /dev/sdb

 

WARNING:DOS-compatible mode is deprecated. It's strongly recommended to

        switch off the mode (command 'c') and change display units to

        sectors (command 'u').

 

Command (m forhelp): p                 ←查看分区信息

 

Disk /dev/sdb:21.5 GB, 21474836480 bytes

255 heads, 63 sectors/track, 2610 cylinders

Units = cylinders of 16065 * 512 = 8225280bytes

Sector size (logical/physical): 512 bytes /512 bytes

I/O size (minimum/optimal): 512 bytes / 512bytes

Disk identifier: 0xae03f6ac

 

  Device Boot      Start         End      Blocks  Id  System

/dev/sdb1               1          14      112423+ 83  Linux

/dev/sdb2              15          21       56227+ 83  Linux

 

Command (m forhelp): d                 ←删除分区

Partition number (1-4): 2              ←选择要删除的分区

 

Command (m forhelp): w                 ←保存并退出

The partition table has been altered!

 

Calling ioctl() to re-read partition table.

Syncing disks.

二、LVM

l  介绍最常用的几个命令：

    1）pvcreate用于将分区或整个硬盘转换成物理卷，主要是添加LVM属性信息并划分PE存储单位。该命令需要使用分区或硬盘设备名作为参数

    2）vgcreate用于将一个或多个物理卷创建为一个卷组，第一个命令参数指定定义的新卷组名称，其后依次指定需要加入到该卷组的物理卷作为参数

    3）lvcreate用于从指定的卷组中分割空间，以创建新的逻辑卷。需要指定逻辑卷大小、名称及所在的卷组名作为参数

    4）lvextend用于动态扩展逻辑卷的空间，当目前使用的逻辑卷空间不足时，可以从所在卷组中分割额外的空间进行扩展

 

# pvcreate /dev/sdb1                             ←转化物理卷

  Physical volume "/dev/sdb1"successfully created

# pvcreate /dev/sdc1                             ←转化物理卷

  Physical volume "/dev/sdc1"successfully created

# vgcreate group /dev/sdb1 /dev/sdc1             ←创建组group

  Volume group "group" successfullycreated

# lvcreate -L 50M -n lv_data group               ←创建逻辑卷lv_data

 Rounding up size to full physical extent 52.00 MiB

 Logical volume "lv_data" created

# lvextend -L +100M /dev/group/lv_data           ←扩展逻辑卷

 Extending logical volume lv_data to 152.00 MiB

 Logical volume lv_data successfully resized

格式化文件系统有3中方法：

1. mkfs -t ext4 /dev/卷组名/逻辑卷名

2. mkfs.ext4 /dev/卷组名/逻辑卷名

3. mke2fs -t ext4 /dev/卷组名/逻辑卷名
   

# mkfs.ext4 /dev/group/lv_data        

mke2fs 1.41.12 (17-May-2010)

Filesystem label=

OS type: Linux

Block size=1024 (log=0)

Fragment size=1024 (log=0)

Stride=0 blocks, Stripe width=0 blocks

38912 inodes, 155648 blocks

7782 blocks (5.00%) reserved for the superuser

First data block=1

Maximum filesystem blocks=67371008

19 block groups

8192 blocks per group, 8192 fragments pergroup

2048 inodes per group

Superblock backups stored on blocks:

       8193, 24577, 40961, 57345, 73729

 

Writing inodetables: done

Creating journal (4096 blocks): done

Writing superblocks and filesystemaccounting information: done

 

This filesystemwill be automatically checked every 37 mounts or

180 days, whichever comes first.  Use tune2fs -c or -i to override.

三、挂载

Linux系统中，文件系统创建后，还需将其安装到Linux目录树的某个位置上才能使用，这个过程称为挂载，文件系统所挂载到的目录称为挂载点。文件系统使用完毕，还可对其进行卸载

1.挂载文件系统

在Linux系统中，磁盘设备被挂接到一个已存在的目录上，以后的磁盘的存取就变成了对该挂接目录的读写访问。通常选择已存在的空目录作为挂接目录，因为如果挂接目录已经包含文件，在挂接操作完成后，原文件将临时被挂接磁盘中的文件覆盖，直到从系统中卸载该磁盘为止。文件系统的挂载，可以在系统引导过程中自动加载，也可以使用命令手工挂载

# mkdir /data                             ←创建挂载点目录           

# mount /dev/group/lv_data /data          ←挂载

# cd /data

# ll

total 12

drwx------ 2 root root 12288 Aug 20 04:47lost+found

2.卸载文件系统

如果系统已挂接的磁盘不再使用，为了节省系统资源，可以将该磁盘从系统中卸下。与挂载相比，卸载文件系统简单很多，卸载文件系统使用umount命令

# umount /dev/group/lv_data               ←卸载

# cd /data

# ll

total 0