使用Hyper-V安装CentOS虚拟机，使用起来非常方便。但遇到磁盘空间不够时，不像Windows虚拟机那样方便给磁盘空间扩容。 总体两分二步：
1. vhdx扩容
关闭虚拟机，然后给磁盘扩容，操作方便网上教程多，这里不再赘述。
2. CentOS扩容
2.1 查看分区表
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 200M 0 part /boot/efi
├─sda2 8:2 0 1G 0 part /boot
└─sda3 8:3 0 8.8G 0 part
├─centos-root 253:0 0 7.8G 0 lvm /
└─centos-swap 253:1 0 1G 0 lvm [SWAP]
以上内容可以看出，sda已经扩容到20G，但sda1+sda2+sda3只有10G说明vhdx扩容成功。
2.2 建立新分区
$ fdisk /dev/sda
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
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)：n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p):
Using default response p
分区号 (2-4，默认 2)：
起始 扇区 (20971520-41943039，默认为 20971520)：
将使用默认值 20971520
Last 扇区, +扇区 or +size{K,M,G} (20971520-41943039，默认为 41943039)：+10G
值超出范围。
Last 扇区, +扇区 or +size{K,M,G} (20971520-41943039，默认为 41943039)：+9.9G
不支持的后缀：“.9G”。
支持：10^N: KB (千字节), MB (兆字节), GB (吉字节)
2^N: K (约千字节), M (约兆字节), G (约吉字节)
Last 扇区, +扇区 or +size{K,M,G} (20971520-41943039，默认为 41943039)：+9G
分区 2 已设置为 Linux 类型，大小设为 9 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。
重读分区表时，发生错误
$ partprobe
Error: 备份 GPT 表不像应该的那样出现在磁盘的末尾。这可能意味这其它操作系统相信磁盘小一些。通过将备份移动到末尾 (并删除旧备份) 来修正？
Warning: Not all of the space available to /dev/sda appears to be used, you can fix the GPT to use all of the space (an extra 20971520 blocks) or continue with the current setting?
查看分区表时，发现新分区未创建成功
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 200M 0 part /boot/efi
├─sda2 8:2 0 1G 0 part /boot
└─sda3 8:3 0 8.8G 0 part
├─centos-root 253:0 0 7.8G 0 lvm /
└─centos-swap 253:1 0 1G 0 lvm [SWAP]
使用 parted 修复分区表
$ parted /dev/sda
GNU Parted 3.1
使用 /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
错误: 备份 GPT 表不像应该的那样出现在磁盘的末尾。这可能意味这其它操作系统相信磁盘小一些。通过将备份移动到末尾 (并删除旧备份) 来修正？
修正/Fix/忽略/Ignore/放弃/Cancel? fix
警告: Not all of the space available to /dev/sda appears to be used, you can fix the GPT to use all of the space (an extra 20971520 blocks) or continue with the current
setting?
修正/Fix/忽略/Ignore? fix
Model: Msft Virtual Disk (scsi)
Disk /dev/sda: 21.5GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name 标志
1 1049kB 211MB 210MB fat16 EFI System Partition 启动
2 211MB 1285MB 1074MB xfs
3 1285MB 10.7GB 9452MB lvm
(parted) p
Model: Msft Virtual Disk (scsi)
Disk /dev/sda: 21.5GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name 标志
1 1049kB 211MB 210MB fat16 EFI System Partition 启动
2 211MB 1285MB 1074MB xfs
3 1285MB 10.7GB 9452MB lvm
(parted) quit
再次建立新分区
$ fdisk /dev/sda
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.
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)：n
分区号 (4-128，默认 4)：
第一个扇区 (34-41943006，默认 20969472)：
Last sector, +sectors or +size{K,M,G,T,P} (20969472-41943006，默认 41943006)：+10G
已创建分区 4
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。
2.3 重读分区表
$ partprobe
重读分区表，正常不会有任何输出
再次查看分区表，可以看到 sda4 分区已经创建好了
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 200M 0 part /boot/efi
├─sda2 8:2 0 1G 0 part /boot
├─sda3 8:3 0 8.8G 0 part
│ ├─centos-root 253:0 0 7.8G 0 lvm /
│ └─centos-swap 253:1 0 1G 0 lvm [SWAP]
└─sda4 8:4 0 10G 0 part
2.4 将 sda4 分区加入 centos-root 分区
$ lvm
lvm> pvcreate /dev/sda4
Physical volume "/dev/sda4" successfully created.
lvm> pvdisplay
--- Physical volume ---
PV Name /dev/sda3
VG Name centos
PV Size 8.80 GiB / not usable 2.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 2253
Free PE 0
Allocated PE 2253
PV UUID D5K7Ds-a0I8-67Kt-LE1J-HKi7-aaKX-CLaJTg
"/dev/sda4" is a new physical volume of "10.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sda4
VG Name
PV Size 10.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID digjnH-8XFC-kMQT-nOEL-y9FJ-ImaB-t8FB7d
lvm> vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 8.80 GiB
PE Size 4.00 MiB
Total PE 2253
Alloc PE / Size 2253 / 8.80 GiB
Free PE / Size 0 / 0
VG UUID f77tkP-7xzc-qcyf-t0JN-OYOQ-ZfLL-PJPD8w
lvm> vgextend centos /dev/sda4
Volume group "centos" successfully extended
lvm> vgdisplay
--- Volume group ---
VG Name centos
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 <18.80 GiB
PE Size 4.00 MiB
Total PE 4812
Alloc PE / Size 2253 / 8.80 GiB
Free PE / Size 2559 / <10.00 GiB
VG UUID f77tkP-7xzc-qcyf-t0JN-OYOQ-ZfLL-PJPD8w
lvm> lvextend -l +100%FREE /dev/centos/root
Size of logical volume centos/root changed from 7.80 GiB (1997 extents) to <17.80 GiB (4556 extents).
Logical volume centos/root successfully resized.
lvm> exit
Exiting.
$ xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=511232 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=2044928, 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=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 2044928 to 4665344
再次查看磁盘容量与分区表，centos-root分区空间已经扩容为17.8G
$ df -h
文件系统 容量 已用 可用 已用% 挂载点
devtmpfs 876M 0 876M 0% /dev
tmpfs 887M 0 887M 0% /dev/shm
tmpfs 887M 8.4M 879M 1% /run
tmpfs 887M 0 887M 0% /sys/fs/cgroup
/dev/mapper/centos-root 18G 7.3G 11G 41% /
/dev/sda2 1014M 215M 800M 22% /boot
/dev/sda1 200M 12M 189M 6% /boot/efi
tmpfs 178M 0 178M 0% /run/user/0
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 200M 0 part /boot/efi
├─sda2 8:2 0 1G 0 part /boot
├─sda3 8:3 0 8.8G 0 part
│ ├─centos-root 253:0 0 17.8G 0 lvm /
│ └─centos-swap 253:1 0 1G 0 lvm [SWAP]
└─sda4 8:4 0 10G 0 part
└─centos-root 253:0 0 17.8G 0 lvm /