KVM虚拟磁盘扩容

1、磁盘扩容分为raw和qcow2两种扩容方式，命令相同，区别是后缀名

[root@daixuan ~]# qemu-img info /data/daixuan1.qcow2 //本身只有9G

p_w_picpath: /data/daixuan1.qcow2

file format: qcow2

virtual size: 10G (10737418240 bytes)

disk size: 10G

cluster_size: 65536

[root@daixuan ~]# qemu-img resize /data/daixuan1.qcow2 +5G  //加5G

Image resized.

[root@daixuan ~]# qemu-img info /data/daixuan1.qcow2 //查看已经+5G，登录后fdisk -l还是10G

p_w_picpath: /data/daixuan1.qcow2

file format: qcow2

virtual size: 15G (16106127360 bytes)

如果需要真正生效，需要destroy，之后start，把配置重新加载

[root@daixuan ~]# virsh destroy daixuan1

[root@daixuan ~]# virsh start daixuan1

[root@daixuan ~]# virsh console daixuan1

fdisk -l   列出系统中所有的磁盘设备和分区表，这里磁盘设备容量已经增加5G

[root@localhost ~]# fdisk -l

Disk /dev/vda: 16.1 GB, 16106127360 bytes

2、但是磁盘挂载的空间并没有增加，依然是8.3G

[root@localhost ~]# df -h //查看可用磁盘总容量和使用容量

Filesystem  Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root 8.3G  685M  7.2G   9% /

tmpfs                246M     0  246M   0% /dev/shm

/dev/vda1             477M   33M  419M   8% /boot

(1)因为新增加的空间还没有划分使用，所以要继续分区：

[root@localhost ~]# fdisk /dev/vda

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): p

Disk /dev/vda: 16.1 GB, 16106127360 bytes

16 heads, 63 sectors/track, 31207 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

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

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

Disk identifier: 0x000dca27

Device Boot      Start         End      Blocks   Id  System

/dev/vda1   *           3        1018      512000   83  Linux

Partition 1 does not end on cylinder boundary.

/dev/vda2            1018       20806     9972736   8e  Linux LVM

Partition 2 does not end on cylinder boundary.

Command (m for help): n

Command action

e   extended

p   primary partition (1-4)

p

Partition number (1-4): 3

First cylinder (1-31207, default 1): 20807

Last cylinder, +cylinders or +size{K,M,G} (20807-31207, default 31207): 31207

Command (m for help): p

Disk /dev/vda: 16.1 GB, 16106127360 bytes

16 heads, 63 sectors/track, 31207 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

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

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

Disk identifier: 0x000dca27

Device Boot      Start         End      Blocks   Id  System

/dev/vda1   *           3        1018      512000   83  Linux

Partition 1 does not end on cylinder boundary.

/dev/vda2            1018       20806     9972736   8e  Linux LVM

Partition 2 does not end on cylinder boundary.

/dev/vda3           20807       31207     5242104   83  Linux

Command (m for help): w

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.

(2)然后再把这个/dev/vda3 加入到lvm里面去：

[root@localhost ~]# ls /dev/vda3 //如果没有这个分区，需要重启一下

[root@localhost ~]# reboot

[root@localhost ~]# pvcreate /dev/vda3  //创建物理卷

Physical volume "/dev/vda3" successfully created

[root@localhost ~]# pvs //查看卷

PV         VG       Fmt  Attr PSize PFree

/dev/vda2  VolGroup     lvm2 a--  9.51g  0

/dev/vda3            lvm2 ---  5.00g  5.00g

[root@localhost ~]# vgextend VolGroup /dev/vda3  //VolGroup虚拟卷扩展，vda3加入到Vol

Volume group "VolGroup" successfully extended

[root@localhost ~]# pvs

PV         VG       Fmt  Attr PSize PFree

/dev/vda2  VolGroup lvm2 a--  9.51g    0

/dev/vda3  VolGroup lvm2 a--  5.00g    0

[root@localhost ~]# vgs    //VFree中5G

VG       #PV #LV #SN Attr   VSize  VFree

VolGroup   2   2   0 wz--n- 14.50g  5.00g

如何把5G加入到lv_root中？

[root@localhost ~]# lvs //查看逻辑卷

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

lv_root VolGroup -wi-ao----   8.54g

lv_swap VolGroup -wi-ao---- 992.00m

[root@localhost ~]# lvextend -l +100%FREE /dev/VolGroup/lv_root  //扩展卷

Size of logical volume VolGroup/lv_root changed from 8.54 GiB (2186 extents) to 13.54 GiB (3465 extents).

Logical volume lv_root successfully resized

[root@localhost ~]# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root 8.3G  685M  7.2G   9% /

tmpfs                246M     0  246M   0% /dev/shm

/dev/vda1              477M   33M  419M   8% /boot

[root@localhost ~]# resize2fs/dev/VolGroup/lv_root

resize2fs 1.41.12 (17-May-2010)

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

old desc_blocks = 1, new_desc_blocks = 1

Performing an on-line resize of /dev/VolGroup/lv_root to 3548160 (4k) blocks.

The filesystem on /dev/VolGroup/lv_root is now 3548160 blocks long.

[root@localhost ~]# df -h

Filesystem              Size  Used Avail Use% Mounted on

/dev/mapper/VolGroup-lv_root 14G 687M   12G   6% /

tmpfs                 246M     0  246M   0% /dev/shm

/dev/vda1              477M   33M  419M   8% /boot

如果提示 This p_w_picpath format does not support resize, 检查一下你qemu-img create的时候，是否有加 preallocation=metadata 选项，如果有，就不能resize了。

(3)另外，如果是增加磁盘，思路是创建磁盘： qemu-img create -f qcow2  /data/daixuan1_2.qcow2 5G关闭虚拟机： virsh destroy daixuan1编辑配置文件： virsh edit daixuan1

复制增加如下：注意是vdb，qcow2

开启虚拟机：virsh start daixuan1进入虚拟机：virsh console daixuan1分区： fdisk /dev/vdb格式化：mkfs.ext4 /dev/vdb

挂载：vim /etc/fstab，添加一行：/dev/vdb  /mnt  ext4   defaults    0 0

mount -a 然后mnt就可以使用了

[root@localhost ~]# cd /mnt

[root@localhost mnt]# touch 23.txt

当然也可以按照上面的思路把 /dev/vdb 加入到 lvm里面去，测试成功，这里省略步骤注： raw格式步骤基本上和qcow2一样。如果提示 This p_w_picpath format does not support resize, 检查一下你qemu-img create的时候，是否有加  preallocation=metadata 选项，如果有，就不能resize了。