CentOS中怎么扩容虚拟机根分区磁盘

CentOS中怎么扩容虚拟机根分区磁盘，针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。

一、关闭你的虚拟机系统

查看镜像大小

qemu-img info test.img

给虚拟机镜像扩容40G

dd if =/dev/zero bs=1024M count=40 >>test.img

使用qemu-img info再看看镜像大小

二、启动虚拟机使用linux下的fdisk工具进行分区

用root用户登录到你的linux系统，查看你系统的分区

# fdisk -l

Disk /dev/sda: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00008d26

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          64      512000   83  Linux

Partition 1 does not end on cylinder boundary.

/dev/sda2              64        2611    20458496   8e  Linux LVM

Disk /dev/mapper/VolGroup-lv_root: 18.9 GB, 18865979392 bytes

255 heads, 63 sectors/track, 2293 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 2080 MB, 2080374784 bytes

255 heads, 63 sectors/track, 252 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00000000

根据提示信息可以判断出此系统的磁盘接口为SCSI，对应“sda”如果上面的红色字体是“hda”，那么此系统的磁盘接口为IDE对应“hda”所以我做一下操作：

# fdisk /dev/sda

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 for help): m //列出fdisk的帮助

Command action

   a   toggle a bootable flag

   b   edit bsd disklabel

   c   toggle the dos compatibility flag

   d   delete a partition

   l   list known partition types

   m   print this menu

   n   add a new partition

   o   create a new empty DOS partition table

   p   print the partition table

   q   quit without saving changes

   s   create a new empty Sun disklabel

   t   change a partition's system id

   u   change display/entry units

   v   verify the partition table

   w   write table to disk and exit

   x   extra functionality (experts only)

Command (m for help): n    //命令n用于添加新分区

Command action

   e   extended

   p   primary partition (1-4)

p  //选择创建主分区"此时

Partition number (1-4): 3  //fdisk会让你选择主分区的编号，如果已经有了主分区sda1，sda2，那么编号就选3，即要创建的该分区为sda3

First cylinder (2611-7832, default 2611): //此时，fdisk又会让你选择该分区的开始值这个就是分区的Start 值（start cylinder）；这里最好直接按回车

Using default value 2611

Last cylinder, +cylinders or +size{K,M,G} (2611-7832, default 7832): //此时，fdisk又会让你选择该分区的开始值这个就是分区的End 值这里最好直接按回车

Using default value 7832

Command (m for help): w //保存所有并退出，分区划分完毕

The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table. The new table will be used at

the next reboot or after you run partprobe(8) or kpartx(8)

Syncing disks.

三、我们的新建分区/dev/sda3，却不是LVM的。所以，接下来使用fdisk将其改成LVM的

# fdisk /dev/sda

Command (m for help): m

Command (m for help): t //改变分区系统id

Partition number (1-4): 3 //指定分区号

Hex code (type L to list codes): 8e //指定要改成的id号，8e代表LVM

Changed system type of partition 3 to 8e (Linux LVM)

Command (m for help): w

四、重启系统后，登陆系统。（一定要重启系统，否则无法扩充新分区）

五、格式化该新添加的分区

# fdisk -l

Disk /dev/sda: 64.4 GB, 64424509440 bytes

255 heads, 63 sectors/track, 7832 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00008d26

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          64      512000   83  Linux

Partition 1 does not end on cylinder boundary.

/dev/sda2              64        2611    20458496   8e  Linux LVM

/dev/sda3            2611        7832    41939020   8e  Linux LVM

Disk /dev/mapper/VolGroup-lv_root: 18.9 GB, 18865979392 bytes

255 heads, 63 sectors/track, 2293 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 2080 MB, 2080374784 bytes

255 heads, 63 sectors/track, 252 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

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

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

Disk identifier: 0x00000000

你会发现多了一块分区

# mkfs -t ext3 /dev/sda3 //在硬盘分区“/dev/sda3”上创建“ext3”文件系统

mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
2621440 inodes, 10484755 blocks
524237 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
320 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
        4096000, 7962624

Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 23 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

此时我们就可以使用该新增分区啦：

六、扩充新分区

# lvs

  LV      VG       Attr       LSize  Pool Origin Data%  Move Log Cpy%Sync Convert

  lv_root VolGroup -wi-ao---- 17.57g

  lv_swap VolGroup -wi-ao----  1.94g

# pvcreate /dev/sda3

  Physical volume "/dev/sda3" successfully created

# pvcreate /dev/sda3 //pvcreate指令用于将物理硬盘分区初始化为物理卷，以便被LVM使用。要创建物理卷必须首先对硬盘进行分区，并且将硬盘分区的类型设置为“8e”后，才能使用pvcreat指令将分区初始化为物理卷

  Physical volume "/dev/sda3" successfully created

# df -h

Filesystem                    Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root   18G  1.7G   15G  10% /

tmpfs                         1.9G     0  1.9G   0% /dev/shm

/dev/sda1                     485M   32M  428M   7% /boot

# vgextend /dev/mapper/VolGroup-lv_root /dev/sda3    //其中是当前需要扩充的lvm组名，可以通过df -h查看，例如我的是： /dev/mapper/VolGroup-lv_root） //vgextend指令用于动态的扩展卷组，它通过向卷组中添加物理卷来增加卷组的容量

  Volume group name VolGroup/lv_root has invalid characters

# vgextend /dev/mapper/VolGroup /dev/sda3    //原来这个组名，是-之前的字符串——这要是没有文章看着对比分析，谁知道啊？

  Volume group "VolGroup" successfully extended

#vgdisplay    //用于显示LNM卷组的元数据信息

  --- Volume group ---

  VG Name               VolGroup

  System ID

  Format                lvm2

  Metadata Areas        2

  Metadata Sequence No  4

  VG Access             read/write

  VG Status             resizable

  MAX LV                0

  Cur LV                2

  Open LV               2

  Max PV                0

  Cur PV                2

  Act PV                2

  VG Size               59.50 GiB

  PE Size               4.00 MiB

  Total PE              15232

  Alloc PE / Size       4994 / 19.51 GiB

  Free  PE / Size       10238 / 39.99 GiB

  VG UUID               Ecv3ml-86eg-LTsH-mALD-mLxW-v3Ao-GEqiFc

(主要查看Free  PE / Size       10238 / 39.99 GiB，说明我们最多可以有39.99GB的扩充空间。我一般选择小于等于39.99GB)

# lvextend -L +39.99G /dev/VolGroup/lv_root /dev/sda3

  Rounding size to boundary between physical extents: 39.99 GiB

  Extending logical volume lv_root to 57.56 GiB

  Logical volume lv_root successfully resized

# e2fsck -f /dev/VolGroup/lv_root

e2fsck 1.41.12 (17-May-2010)

/dev/VolGroup/lv_root is mounted.

e2fsck: Cannot continue, aborting.

# resize2fs  /dev/VolGroup/lv_root（如果这一步报错了改用xfs_growfs/dev/VolGroup/lv_root原因据说是xfs文件系统）

resize2fs 1.41.12 (17-May-2010)

Filesystem at /dev/VolGroup/lv_root is mounted on /; on-line resizing required

old desc_blocks = 2, new_desc_blocks = 4

Performing an on-line resize of /dev/VolGroup/lv_root to 15089664 (4k) blocks.

The filesystem on /dev/VolGroup/lv_root is now 15089664 blocks long.

# df -h

Filesystem                    Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root   57G  1.7G   53G   3% /

tmpfs                         1.9G     0  1.9G   0% /dev/shm

/dev/sda1                     485M   32M  428M   7% /boot

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