kvm虚拟机磁盘扩容

虚拟机基础镜像制作完成后，磁盘容量及固定了，如果遇到需要扩容磁盘容量的情况，我们如何基于当前镜像快速扩容满足需求呢？本文主要介绍如何使用qemu-img resize和virt-resise工具对虚拟机镜像分区扩容，以及两者的区别。

qemu-img resize
#

本文示例中CentOS7虚拟机镜像的系统分区为dos标准分区，基础镜像磁盘大小为50G

[root@kvm-1 sty_vm1]# qemu-img info img-centos7.qcow2
image: img-centos7.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 2.1G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

qemu-img resize扩容20G

[root@kvm-1 sty_vm1]# qemu-img resize img-centos7.qcow2 +20G
Image resized.

#磁盘镜像文件已经扩容
[root@kvm-1 sty_vm1]# qemu-img info img-centos7.qcow2
image: img-centos7.qcow2
file format: qcow2
virtual size: 70G (75161927680 bytes)
disk size: 2.1G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

虚拟机有三个分区，/dev/vda3挂载到根文件系统

[root@kvm-1 sty_vm1]# virt-filesystems --long -h --all  -a img-centos7.qcow2
Name       Type        VFS   Label  MBR  Size  Parent
/dev/sda1  filesystem  xfs   -      -    1.0G  -
/dev/sda2  filesystem  swap  -      -    3.9G  -
/dev/sda3  filesystem  xfs   -      -    45G   -
/dev/sda1  partition   -     -      83   1.0G  /dev/sda
/dev/sda2  partition   -     -      82   3.9G  /dev/sda
/dev/sda3  partition   -     -      83   45G   /dev/sda
/dev/sda   device      -     -      -    50G   -

#登录到虚拟机查看挂载点
[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0   70G  0 disk
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 45.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot

虚拟机磁盘文件扩容20G之后，我们还需要扩容文件系统。

1.创建新分区的方式
#

使用fdisk新建一个主分区/dev/vda4

[root@kvm-1 sty_vm1]# virsh start sty_vm1
域 sty_vm1 已开始

[root@localhost] ~$ fdisk /dev/vda
欢迎使用 fdisk (util-linux 2.23.2)。

更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。

命令(输入 m 获取帮助)：p

磁盘 /dev/vda：75.2 GB, 75161927680 字节，146800640 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0x0009a1e8

   设备 Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     2099199     1048576   83  Linux
/dev/vda2         2099200    10227711     4064256   82  Linux swap / Solaris
/dev/vda3        10227712   104857599    47314944   83  Linux

命令(输入 m 获取帮助)：n
Partition type:
   p   primary (3 primary, 0 extended, 1 free)
   e   extended
Select (default e): p
已选择分区 4
起始 扇区 (104857600-146800639，默认为 104857600)：                        <-- 回车键使用默认值
将使用默认值 104857600
Last 扇区, +扇区 or +size{K,M,G} (104857600-146800639，默认为 146800639)： <-- 回车键使用默认值
将使用默认值 146800639
分区 4 已设置为 Linux 类型，大小设为 20 GiB

命令(输入 m 获取帮助)：w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
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)
正在同步磁盘。

[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0   70G  0 disk
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 45.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot
# 刷新分区表，可以看到新建的磁盘分区
[root@localhost] ~$ partprobe
[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0   70G  0 disk
├─vda4 253:4    0   20G  0 part
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 45.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot

[root@localhost] ~$ mkfs.xfs /dev/vda4
meta-data=/dev/vda4              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@localhost] ~$ mkdir /data0
[root@localhost] ~$ mount /dev/vda4 /data0
[root@localhost] ~$ df -h
文件系统        容量  已用  可用 已用% 挂载点
devtmpfs        3.8G     0  3.8G    0% /dev
tmpfs           3.8G     0  3.8G    0% /dev/shm
tmpfs           3.8G  8.5M  3.8G    1% /run
tmpfs           3.8G     0  3.8G    0% /sys/fs/cgroup
/dev/vda3        46G  1.9G   44G    5% /
/dev/vda1      1014M  293M  722M   29% /boot
tmpfs           772M     0  772M    0% /run/user/0
/dev/vda4        20G   33M   20G    1% /data0

2.扩容已有分区的方式
#

基于上面的基础镜像，直接扩容根文件系统。

登录到虚拟机可以看到最后一个分区为/dev/vda3，并挂载到了根目录，可以直接使用fdisk重建分区vda3

[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0   50G  0 disk
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 45.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot
[root@localhost] ~$ fdisk -l /dev/vda

Disk /dev/vda: 53.7 GB, 53687091200 bytes, 104857600 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: 0x0009a1e8

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     2099199     1048576   83  Linux
/dev/vda2         2099200    10227711     4064256   82  Linux swap / Solaris
/dev/vda3        10227712   104857599    47314944   83  Linux

如果vda3后面还有其他分区，fdisk重建vda3时需要删除vda3之后的所有分区，数据会被清除

使用fdisk重建主分区vda3

[root@kvm-1 sty_vm1]# qemu-img resize img-centos7.qcow2 +50G
Image resized.

[root@localhost] ~$ fdisk /dev/vda
欢迎使用 fdisk (util-linux 2.23.2)。

更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。


命令(输入 m 获取帮助)：p

磁盘 /dev/vda：107.4 GB, 107374182400 字节，209715200 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0x0009a1e8

   设备 Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048     2099199     1048576   83  Linux
/dev/vda2         2099200    10227711     4064256   82  Linux swap / Solaris
/dev/vda3        10227712   104857599    47314944   83  Linux

命令(输入 m 获取帮助)：d
分区号 (1-3，默认 3)：
分区 3 已删除

命令(输入 m 获取帮助)：n
Partition type:
   p   primary (2 primary, 0 extended, 2 free)
   e   extended
Select (default p):
Using default response p
分区号 (3,4，默认 3)：
起始 扇区 (10227712-209715199，默认为 10227712)：
将使用默认值 10227712
Last 扇区, +扇区 or +size{K,M,G} (10227712-209715199，默认为 209715199)：
将使用默认值 209715199
分区 3 已设置为 Linux 类型，大小设为 95.1 GiB

命令(输入 m 获取帮助)：w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
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)
正在同步磁盘。
# 刷新分区表
[root@localhost] ~$ partprobe
[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0  100G  0 disk
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 95.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot

# 磁盘分区已经扩容，但文件系统并没有
[root@localhost] ~$ df -Th /
文件系统       类型  容量  已用  可用 已用% 挂载点
/dev/vda3      xfs    46G  1.9G   44G    5% /

# 扩容文件系统
[root@localhost] ~$ xfs_growfs /dev/vda3
meta-data=/dev/vda3              isize=512    agcount=6, agsize=2301824 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=11828736, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=4495, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 11828736 to 24935936

[root@localhost] ~$  df -Th /
文件系统       类型  容量  已用  可用 已用% 挂载点
/dev/vda3      xfs    96G  1.9G   94G    2% /

virt-resize
#

virt-resize基于拷贝镜像模式，对指定的系统分区扩容，支持windows

1.Centos7分区扩容
#

# 1.查看系统分区情况
[root@kvm-1 sty_vm1]# virt-filesystems --long -h --all  -a img-centos7.qcow2
Name       Type        VFS   Label  MBR  Size  Parent
/dev/sda1  filesystem  xfs   -      -    1.0G  -
/dev/sda2  filesystem  swap  -      -    3.9G  -
/dev/sda3  filesystem  xfs   -      -    45G   -
/dev/sda1  partition   -     -      83   1.0G  /dev/sda
/dev/sda2  partition   -     -      82   3.9G  /dev/sda
/dev/sda3  partition   -     -      83   45G   /dev/sda
/dev/sda   device      -     -      -    50G   -

# 2.创建一个新的空镜像文件，大小为扩容后的磁盘容量
[root@kvm-1 sty_vm1]# qemu-img create -f qcow2 img-centos7+20G.qcow2 70G
Formatting 'img-centos7+20G.qcow2', fmt=qcow2 size=75161927680 cluster_size=65536 lazy_refcounts=off refcount_bits=16

# 3.对指定分区/dev/sda3扩容
[root@kvm-1 sty_vm1]# virt-resize --expand /dev/sda3 img-centos7.qcow2 img-centos7+20G.qcow2
[   0.0] Examining img-centos7.qcow2
**********

Summary of changes:

/dev/sda1: This partition will be left alone.

/dev/sda2: This partition will be left alone.

virt-resize: warning: unknown/unavailable method for expanding the xfs
filesystem on /dev/sda3
/dev/sda3: This partition will be resized from 45.1G to 65.1G.

**********
[   2.7] Setting up initial partition table on img-centos7+20G.qcow2
[   2.9] Copying /dev/sda1
[   4.3] Copying /dev/sda2
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ --:--
[   7.0] Copying /dev/sda3
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00

Resize operation completed with no errors.  Before deleting the old disk,
carefully check that the resized disk boots and works correctly.

[root@kvm-1 sty_vm1]# mv img-centos7+20G.qcow2 img-centos7.qcow2
[root@kvm-1 sty_vm1]# virsh start sty_vm1
域 sty_vm1 已开始

[root@localhost] ~$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda    253:0    0   70G  0 disk
├─vda2 253:2    0  3.9G  0 part
├─vda3 253:3    0 65.1G  0 part /
└─vda1 253:1    0    1G  0 part /boot
[root@localhost] ~$ df -h
文件系统        容量  已用  可用 已用% 挂载点
devtmpfs        3.8G     0  3.8G    0% /dev
tmpfs           3.8G     0  3.8G    0% /dev/shm
tmpfs           3.8G  8.5M  3.8G    1% /run
tmpfs           3.8G     0  3.8G    0% /sys/fs/cgroup
/dev/vda3        46G  2.0G   44G    5% /
/dev/vda1      1014M  314M  701M   31% /boot
tmpfs           772M     0  772M    0% /run/user/0

# 4.登录虚拟机使用xfs_growfs扩容xfs文件系统
[root@localhost] ~$ xfs_growfs /dev/vda3
meta-data=/dev/vda3              isize=512    agcount=6, agsize=2301824 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=11828736, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=4495, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 11828736 to 17071296
[root@localhost] ~$ df -Th
文件系统       类型      容量  已用  可用 已用% 挂载点
devtmpfs       devtmpfs  3.8G     0  3.8G    0% /dev
tmpfs          tmpfs     3.8G     0  3.8G    0% /dev/shm
tmpfs          tmpfs     3.8G  8.5M  3.8G    1% /run
tmpfs          tmpfs     3.8G     0  3.8G    0% /sys/fs/cgroup
/dev/vda3      xfs        66G  1.9G   64G    3% /
/dev/vda1      xfs      1014M  325M  690M   32% /boot
tmpfs          tmpfs     772M     0  772M    0% /run/user/0

2.WinServer分区扩容
#

WindowsServer2019的虚拟机镜像扩容

# 1.查看系统分区情况
root@kvm-1 ori]# virt-filesystems --long -h --all  -a  win2019-ori.qcow2
Name       Type        VFS   Label         MBR  Size  Parent
/dev/sda1  filesystem  ntfs  系统保留  -    549M  -
/dev/sda2  filesystem  ntfs  -             -    49G   -
/dev/sda1  partition   -     -             07   549M  /dev/sda
/dev/sda2  partition   -     -             07   49G   /dev/sda
/dev/sda   device      -     -             -    50G   -

# 2.创建一个新的空镜像文件，大小为扩容后的磁盘容量
[root@kvm-1 ori]# qemu-img create -f qcow2 win2019-ori+20G.qcow2 70G
Formatting 'win2019-ori+20G.qcow2', fmt=qcow2 size=75161927680 cluster_size=65536 lazy_refcounts=off refcount_bits=16

# 3.对指定分区/dev/sda2扩容
root@kvm-1 ori]# virt-resize --expand  /dev/sda2 win2019-ori.qcow2 win2019-ori+20G.qcow2
[   0.0] Examining win2019-ori.qcow2
**********

Summary of changes:

/dev/sda1: This partition will be left alone.

/dev/sda2: This partition will be resized from 49.5G to 69.5G.  The
filesystem ntfs on /dev/sda2 will be expanded using the ‘ntfsresize’
method.

**********
[   2.6] Setting up initial partition table on win2019-ori+20G.qcow2
[   2.8] Copying /dev/sda1
[   3.4] Copying /dev/sda2
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 
00:00
[  88.8] Expanding /dev/sda2 using the ‘ntfsresize’ method
virt-resize: error: libguestfs error: ntfsresize: /dev/sda2: ntfsresize
v2015.3.14 (libntfs-3g)
Device name        : /dev/sda2
NTFS volume version: 3.1
Cluster size       : 4096 bytes
Current volume size: 53109322240 bytes (53110 MB)
Current device size: 74583965696 bytes (74584 MB)
New volume size    : 74583962112 bytes (74584 MB)
Checking filesystem consistency ...
Accounting clusters ...
Cluster accounting failed at 19922 (0x4dd2): missing cluster in $Bitmap
Cluster accounting failed at 19923 (0x4dd3): missing cluster in $Bitmap
Cluster accounting failed at 19924 (0x4dd4): missing cluster in $Bitmap
Cluster accounting failed at 19925 (0x4dd5): missing cluster in $Bitmap
Cluster accounting failed at 19926 (0x4dd6): missing cluster in $Bitmap
Cluster accounting failed at 19927 (0x4dd7): missing cluster in $Bitmap
Cluster accounting failed at 19928 (0x4dd8): missing cluster in $Bitmap
Cluster accounting failed at 19929 (0x4dd9): missing cluster in $Bitmap
Cluster accounting failed at 20146 (0x4eb2): extra cluster in $Bitmap
Cluster accounting failed at 20147 (0x4eb3): extra cluster in $Bitmap
Filesystem check failed! Totally 15840 cluster accounting mismatches.
ERROR: NTFS is inconsistent. Run chkdsk /f on Windows then reboot it TWICE!
The usage of the /f parameter is very IMPORTANT! No modification was
and will be made to NTFS by this software until it gets repaired.

If reporting bugs, run virt-resize with debugging enabled and include the
complete output:

  virt-resize -v -x [...]

第一次执行virt-resize报错，执行到ntfsresize时提示NTFS文件系统检查失败.查询官方文档了解到，需要对虚拟机所有分区执行chkdsk /f，重启后正常关机

WINDOWS CHKDSK
Windows disks which use NTFS must be consistent before virt-resize can be used. If the ntfsresize operation fails, try booting the original VM and running chkdsk /f on all NTFS partitions, then shut down the VM cleanly. For further information see: https://bugzilla.redhat.com/show_bug.cgi?id=975753
After resize Windows may initiate a lengthy “chkdsk” on first boot if NTFS partitions have been expanded. This is just a safety check and (unless it find errors) is nothing to worry about.
引用自：https://libguestfs.org/virt-resize.1.html

本文windows虚拟机只有一个C盘，登录vm执行chkdsk C: /f，重启完成后再关机

PS C:\Users\Administrator> chkdsk C: /f 
文件系统的类型是 NTFS。
无法锁定当前驱功器。

由于该卷正被另一进程使用，无法运行 Chkdsk。
是否计划在下一次系统重新启动时检查此卷？（Y/N） y 

将在下一次系统重新启动时检查此卷。

再次执行virt-resize --expand

[root@kvm-1 ori]# virt-resize --expand  /dev/sda2 win2019-ori.qcow2 win2019-ori+20G.qcow2
[   0.0] Examining win2019-ori.qcow2
**********

Summary of changes:

/dev/sda1: This partition will be left alone.

/dev/sda2: This partition will be resized from 49.5G to 69.5G.  The
filesystem ntfs on /dev/sda2 will be expanded using the ‘ntfsresize’
method.

**********
[  14.6] Setting up initial partition table on win2019-ori+20G.qcow2
[  14.8] Copying /dev/sda1
[  15.4] Copying /dev/sda2
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00
[ 103.6] Expanding /dev/sda2 using the ‘ntfsresize’ method

Resize operation completed with no errors.  Before deleting the old disk,
carefully check that the resized disk boots and works correctly.

# /dev/sda2 NTFS文件系统已成功扩容
[root@kvm-1 ori]# virt-filesystems --long -h --all  -a  win2019-ori+20G.qcow2
Name       Type        VFS   Label         MBR  Size  Parent
/dev/sda1  filesystem  ntfs  系统保留  -    549M  -
/dev/sda2  filesystem  ntfs  -             -    69G   -
/dev/sda1  partition   -     -             07   549M  /dev/sda
/dev/sda2  partition   -     -             07   69G   /dev/sda
/dev/sda   device      -     -             -    70G   -

两种工具对比
#

	qemu-img resize + fdisk	virt-resise
操作系统	Linux	Linux、Windows
快照镜像扩容	不支持对有快照的镜像扩容	支持
主分区扩容	只支持最后一个主分区的无损扩容	支持所有主分区无损扩容
扩展分区扩容	不支持	不支持
扩容速度	命令行操作，较快	复制模式，和磁盘大小有关，越大越慢