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目前很多VPS或者云主机出于数据保护机制，主机都可以最少划分2块硬盘，一块用来存放用户数据（即网站数据等），一块用来存放系统，这样在您的系统出现问题之后后台选择重装系统，所以在购买VPS或者云主机之后，要手动将另外一块硬盘挂载到用户数据的目录。这个机制有一个缺点就是存放系统的分区将无法应用于用户数据（网站数据等），所以如果您需要充分利用您的磁盘，您可以挂载磁盘为LVM格式。此教程就是挂载磁盘为LVM格式，这样系统分区的磁盘也可以用来存放网页数据（存放是由系统自动分配），按此方法挂载控制面板重装系统数据会丢失！请注意备份数据！如果你想实现重装系统数据不丢失请查看：Linux VPS 挂载磁盘ext3格式(重装系统数据不丢失)

下面教程开始：

[root@MyVPS ~]# fdisk -l //

Disk /dev/xvda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvda1 * 1 13 104391 83 Linux
/dev/xvda2 14 1044 8281507+ 8e Linux LVM
/dev/xvda3 1045 1305 2096482+ 8e Linux LVM

Disk /dev/xvdb: 7516 MB, 7516192768 bytes
255 heads, 63 sectors/track, 913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/xvdb doesn’t contain a valid partition table

[root@MyVPS ~]#df -hal //

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
9.3G 1.2G 7.7G 13% /
proc 0 0 0 – /proc
sysfs 0 0 0 – /sys
devpts 0 0 0 – /dev/pts
/dev/xvda1 99M 29M 66M 31% /boot
tmpfs 151M 0 151M 0% /dev/shm
none 0 0 0 – /proc/sys/fs/binfmt_misc
sunrpc 0 0 0 – /var/lib/nfs/rpc_pipefs

[root@MyVPS ~]#fdisk /dev/xvdb //

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won’t be recoverable.

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

Command (m for help):n //

Command action
e extended
p primary partition (1-4)

p //

 

Partition number (1-4): 1 //

 

First cylinder (1-913, default 1)://

Using default value 1

Last cylinder or +size or +sizeM or +sizeK (1-913, default 913)://

Using default value 913

Command (m for help): t //

Selected partition 1

Hex code (type L to list codes):8e //

Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help):w //

The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

[root@MyVPS ~]#reboot //

Broadcast message from root (pts/0) (Mon Aug 15 00:43:03 2011):

The system is going down for reboot NOW!
[root@MyVPS ~]#
Connection closed by foreign host.

Type `help’ to learn how to use Xshell prompt.
Xshell:\>

Connecting to :22…
Connection established.
Escape character is ‘^@]’.

Last login: Mon Aug 15 00:41:06 2011 from

[root@MyVPS1280 ~]#fdisk -l //

Disk /dev/xvda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvda1 * 1 13 104391 83 Linux
/dev/xvda2 14 1044 8281507+ 8e Linux LVM
/dev/xvda3 1045 1305 2096482+ 8e Linux LVM

Disk /dev/xvdb: 7516 MB, 7516192768 bytes
255 heads, 63 sectors/track, 913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvdb1 1 913 7333641 8e Linux LVM

[root@MyVPS1280 ~]#pvcreate /dev/xvdb1 //

Physical volume “/dev/xvdb1” successfully created

[root@MyVPS1280 ~]#vgextend VolGroup00 /dev/xvdb1 //

Volume group “VolGroup00” successfully extended

[root@MyVPS1280 ~]# vgdisplay //

— Volume group —
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 6
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 3
Act PV 3
VG Size 16.81 GB
PE Size 32.00 MB
Total PE 538
Alloc PE / Size 315 / 9.84 GB
Free PE / Size 223 / 6.97 GB
VG UUID ONGPxy-HBvY-xrrQ-IjEW-PIiO-2cX7-tg6tuI

[root@MyVPS1280 ~]# lvresize -L +6G /dev/VolGroup00/LogVol00 //

Extending logical volume LogVol00 to 15.59 GB
Logical volume LogVol00 successfully resized

[root@MyVPS1280 ~]#resize2fs /dev/VolGroup00/LogVol00 //

resize2fs 1.39 (29-May-2006)
Filesystem at /dev/VolGroup00/LogVol00 is mounted on /; on-line resizing required
Performing an on-line resize of /dev/VolGroup00/LogVol00 to 4087808 (4k) blocks.
The filesystem on /dev/VolGroup00/LogVol00 is now 4087808 blocks long.

[root@MyVPS1280 ~]# vgdisplay //

— Volume group —
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 3
Act PV 3
VG Size 16.81 GB
PE Size 32.00 MB
Total PE 538
Alloc PE / Size 507 / 15.84 GB
Free PE / Size 31 / 992.00 MB
VG UUID ONGPxy-HBvY-xrrQ-IjEW-PIiO-2cX7-tg6tuI

[root@MyVPS1280 ~]# lvresize -L +992M /dev/VolGroup00/LogVol00 //

Extending logical volume LogVol00 to 16.56 GB
Logical volume LogVol00 successfully resized

[root@MyVPS1280 ~]# resize2fs /dev/VolGroup00/LogVol00 //

resize2fs 1.39 (29-May-2006)
Filesystem at /dev/VolGroup00/LogVol00 is mounted on /; on-line resizing required
Performing an on-line resize of /dev/VolGroup00/LogVol00 to 4341760 (4k) blocks.
The filesystem on /dev/VolGroup00/LogVol00 is now 4341760 blocks long.

[root@MyVPS1280 ~]#vgdisplay //

— Volume group —
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 3
Act PV 3
VG Size 16.81 GB
PE Size 32.00 MB
Total PE 538
Alloc PE / Size 538 / 16.81 GB
Free PE / Size 0 / 0
VG UUID ONGPxy-HBvY-xrrQ-IjEW-PIiO-2cX7-tg6tuI

[root@MyVPS1280 ~]# df -hal //

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
17G 1.2G 15G 8% /
proc 0 0 0 – /proc
sysfs 0 0 0 – /sys
devpts 0 0 0 – /dev/pts
/dev/xvda1 99M 29M 66M 31% /boot
tmpfs 151M 0 151M 0% /dev/shm
none 0 0 0 – /proc/sys/fs/binfmt_misc
sunrpc 0 0 0 – /var/lib/nfs/rpc_pipefs

注意事项：
1.教程所用主机为CentOS系统，不同Linux、不同服务器的VPS的卷标（本教程中那个的VolGroup00-LogVol00）可能不同，使用df -hal命令可以查看卷标。
2.如果你使用的不是基本套餐或者你的硬盘不是15G，那么你两次操作需要增加的容量要以你vgdisplay所看到的为准，(vgidsplay里面的Free PE/Size显示的就是可扩容容量)。我们只所以分两次扩容是由于1024的进制差别造成的，我们所实际看到的容量6.97G并不能直接一次扩容，所以我们可以先扩容整数部分，然后扩容以M为单位的部分。
3.系统重装后的重装扩展处理（仅格式化系统盘）
系统重装后，直接执行resize2fs进行动态扩容即可
resize2fs /dev/VolGroup2011/LogVol00
4.PVs missing导致LVM无法重新扩容的解决办法
运行vgextend/vgdisplay返回错误:
Couldn’t find device with uuid ************************
Cannot change VG VolGroup2011 while PVs are missing.
此时可以运行:
vgreduce VolGroup2011 –removemissing
然后重新扩容LVM即可