KVM的热添加技术之硬盘管理

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

版权声明：原创作品，谢绝转载！否则将追究法律责任。

目录

• 一.kvm虚拟机热添加硬盘
  • 1.查看KVM虚拟机现状
  • 2.创建一块qcow2磁盘类型设备
  • 3.为指定KVM虚拟机热添加磁盘
  • 4.KVM虚拟机验证添加硬盘
  • 5.KVM虚拟机格式化新磁盘并测试
  • 6.移除KVM虚拟机的磁盘设备
• 二.kvm虚拟机磁盘的扩容
  • 1.KVM虚拟机扩容规范操作
  • 2.KVM虚拟机磁盘扩容案例
    • 2.1 实验环境准备
    • 2.2 KVM虚拟机卸载挂载点
    • 2.3 在KVM宿主机中移除需要扩容的磁盘设备
    • 2.4 在KVM宿主机扩容磁盘设备
    • 2.5 在KVM宿主机附加硬盘到虚拟机
    • 2.6 在KVM虚拟机重新挂载硬盘设备
    • 2.7 更新vb*文件系统的元数据
• 三.KVM热添加硬盘永久生效
  • 1.临时生效的配置重启虚拟机配置丢失
  • 2.永久配置命令

一.kvm虚拟机热添加硬盘

1.查看KVM虚拟机现状

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 17:49:46 on ttyS0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux
[root@yinzhengjie-kvm01 ~]# 

2.创建一块qcow2磁盘类型设备

[root@yinzhengjie-kvm189 ~]# virsh list 
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# qemu-img create -f qcow2 /opt/yinzhengjie-kvm01_disk01.qcow2 20G
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# ll -h /opt/yinzhengjie-kvm01_disk01.qcow2 
-rw-r--r--. 1 root root 193K Apr  9 18:10 /opt/yinzhengjie-kvm01_disk01.qcow2
[root@yinzhengjie-kvm189 ~]# 


温馨提示:
	个人建议创建虚拟机磁盘的时候，建议前缀和虚拟机名称保持一致，然后使用"_"作为连接符，后续才是我们自定义的磁盘名称。

3.为指定KVM虚拟机热添加磁盘

[root@yinzhengjie-kvm189 ~]# virsh attach-disk yinzhengjie-kvm01 /opt/yinzhengjie-kvm01_disk01.qcow2 vdb --subdriver qcow2


温馨提示:
	如果上面的"vbd"在KVM虚拟机中已经被使用了，则可能指定的盘符命名无效哟，甚至KVM虚拟机会自动修改盘符的名称呢~比如变成了"vdc"之类的。

4.KVM虚拟机验证添加硬盘

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 17:57:05 on ttyS0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux

Disk /dev/vdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

[root@yinzhengjie-kvm01 ~]# 

5.KVM虚拟机格式化新磁盘并测试

[root@yinzhengjie-kvm01 ~]# mkfs.xfs /dev/vdb 
meta-data=/dev/vdb               isize=512    agcount=4, agsize=1310720 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=5242880, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# mount /dev/vdb /mnt/
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
/dev/vdb         20G   33M   20G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# cp /etc/os-release /mnt/
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# ll /mnt/
total 4
-rw-r--r--. 1 root root 393 Apr  9 18:17 os-release
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# umount /mnt 
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# ll /mnt
total 0
[root@yinzhengjie-kvm01 ~]# 

6.移除KVM虚拟机的磁盘设备

	1.移除磁盘设备(如上图所示)
[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh detach-disk yinzhengjie-kvm01 vdb
Disk detached successfully

[root@yinzhengjie-kvm189 ~]# 


	2.连接KVM虚拟机测试是否移除成功(如下图所示)
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 18:12:24 on ttyS0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux
[root@yinzhengjie-kvm01 ~]#

二.kvm虚拟机磁盘的扩容

1.KVM虚拟机扩容规范操作

- 1.在KVM虚拟机中卸载需要扩容的挂载点;
- 2.在KVM宿主机中移除需要扩容的磁盘设备;
- 3.在KVM宿主机使用"qemu-img resize"工具扩容磁盘设备;
- 4.在KVM宿主机附加硬盘到虚拟机;
- 5.在KVM虚拟机重新挂载硬盘设备;
- 6.更新vb*文件系统的元数据;


温馨提示:
	这种方式不仅仅适用于咱们自己使用的KVM环境，也适合所有云环境主机的磁盘扩容流程哟~你可以使用阿里云或者腾讯云测试。

2.KVM虚拟机磁盘扩容案例

2.1 实验环境准备

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
/dev/vdc         20G   33M   20G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux

Disk /dev/vdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# ll /mnt/
total 4
-rw-r--r--. 1 root root 393 Apr  9 18:17 os-release
[root@yinzhengjie-kvm01 ~]# 


温馨提示:
	本案例就是咱们的实验环境，你也可以根据自己的情况进行微调即可。

2.2 KVM虚拟机卸载挂载点

[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
/dev/vdc         20G   33M   20G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# umount /mnt/
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
[root@yinzhengjie-kvm01 ~]# 

2.3 在KVM宿主机中移除需要扩容的磁盘设备

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]#
[root@yinzhengjie-kvm189 ~]# virsh detach-disk yinzhengjie-kvm01 vdc
Disk detached successfully

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 18:37:05 on ttyS0
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux
[root@yinzhengjie-kvm01 ~]# 

2.4 在KVM宿主机扩容磁盘设备

[root@yinzhengjie-kvm189 ~]# qemu-img info /opt/yinzhengjie-kvm01_disk01.qcow2 
image: /opt/yinzhengjie-kvm01_disk01.qcow2
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 11M
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# qemu-img resize /opt/yinzhengjie-kvm01_disk01.qcow2 40G
Image resized.
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# qemu-img info /opt/yinzhengjie-kvm01_disk01.qcow2 
image: /opt/yinzhengjie-kvm01_disk01.qcow2
file format: qcow2
virtual size: 40G (42949672960 bytes)
disk size: 27M
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# ll -h /opt/yinzhengjie-kvm01_disk01.qcow2
-rw-r--r--. 1 root root 12M Apr  9 18:46 /opt/yinzhengjie-kvm01_disk01.qcow2
[root@yinzhengjie-kvm189 ~]# 

2.5 在KVM宿主机附加硬盘到虚拟机

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh attach-disk yinzhengjie-kvm01 /opt/yinzhengjie-kvm01_disk01.qcow2 vdc --subdriver qcow2
Disk attached successfully

[root@yinzhengjie-kvm189 ~]# 

2.6 在KVM虚拟机重新挂载硬盘设备

[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux

Disk /dev/vdc: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# mount /dev/vdc /mnt/
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# ll /mnt/
total 4
-rw-r--r--. 1 root root 393 Apr  9 18:17 os-release
[root@yinzhengjie-kvm01 ~]# 

2.7 更新vb*文件系统的元数据

[root@yinzhengjie-kvm01 ~]# df -h | grep mnt  # 注意看，磁盘的大小貌似没有识别到磁盘扩容了
/dev/vdc         20G   33M   20G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# xfs_growfs /dev/vdc  # 更新xfs文件系统的元数据(超级块)信息
meta-data=/dev/vdc               isize=512    agcount=4, agsize=1310720 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=5242880, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 5242880 to 10485760
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# df -h | grep mnt  # 不难发现，数据更新后，就可以识别到40GB磁盘啦~
/dev/vdc         40G   33M   40G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 

三.KVM热添加硬盘永久生效

1.临时生效的配置重启虚拟机配置丢失

	1.重启前查看虚拟机信息
[root@yinzhengjie-kvm189 ~]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     yinzhengjie-kvm01              running

[root@yinzhengjie-kvm189 ~]# 
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 18:43:50 on ttyS0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
/dev/vdc         40G   33M   40G   1% /mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# umount /mnt/
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# df -h | grep mnt
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux

Disk /dev/vdc: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

[root@yinzhengjie-kvm01 ~]# 



	2.重启KVM虚拟机
[root@yinzhengjie-kvm189 ~]# virsh reboot yinzhengjie-kvm01 
Domain yinzhengjie-kvm01 is being rebooted

[root@yinzhengjie-kvm189 ~]# 


	3.验证磁盘是否丢失(很明显，磁盘配置丢失了，因为KVM虚拟机启动时会加载配置文件)
[root@yinzhengjie-kvm189 ~]# virsh console yinzhengjie-kvm01 
Connected to domain yinzhengjie-kvm01
Escape character is ^]

CentOS Linux 7 (Core)
Kernel 3.10.0-1160.el7.x86_64 on an x86_64

yinzhengjie-kvm01 login: root
Password: 
Last login: Tue Apr  9 19:07:06 on ttyS0
[root@yinzhengjie-kvm01 ~]# 
[root@yinzhengjie-kvm01 ~]# fdisk -l

Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000b20d3

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048    20971519    10484736   83  Linux
[root@yinzhengjie-kvm01 ~]# 

2.永久配置命令

KVM虚拟机添加磁盘的两种方式:
	- 永久添加磁盘(只是把配置写入到配置文件中，但需要重启虚拟机生效)
virsh attach-disk yinzhengjie-kvm01 /opt/yinzhengjie-kvm01_disk01.qcow2 vdb --subdriver qcow2 --config

	- 临时生效(重启后就会失效)
virsh attach-disk yinzhengjie-kvm01 /opt/yinzhengjie-kvm01_disk01.qcow2 vdb --subdriver qcow2
	
	
KVM虚拟机移除磁盘的两种方式:
	- 永久移除磁盘(只是把配置写入到配置文件中，但需要重启虚拟机生效)
virsh detach-disk yinzhengjie-kvm01 vdb --config

	- 临时生效(重启后就会失效)
virsh detach-disk yinzhengjie-kvm01 vdb
	
	

温馨提示:
	如果想要验证是否永久生效，可以使用"virsh edit yinzhengjie-kvm01"命令来观察虚拟机的配置文件，主要查看以下字段信息即可:
<domain type='kvm'>
  ...
  <devices>
    ...
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/opt/yinzhengjie-kvm01.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </disk>
	...