背景：
当初装系统的时候，磁盘空间分的太小了，不够用。想增加点磁盘空间给服务器。
ESXI部署的Centos7系统。
操作：
1.现在esxi上面给虚拟机对应磁盘的空间调大，这个很简单。
2.进入虚拟机，df -h ,fdisk -l 命令查看磁盘状况，发现磁盘大小，可用空间并没有变化，这很正常。
[root@kafka1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 908M 0 908M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.9M 911M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/mapper/centos-root 14G 2.8G 11G 21% /
/dev/sda1 1014M 182M 833M 18% /boot
tmpfs 184M 0 184M 0% /run/user/0
[root@kafka1 ~]# fdisk -l
Disk /dev/sda: 17.2 GB, 17179869184 bytes, 33554432 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: 0x000aa121
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
Disk /dev/mapper/centos-root: 14.4 GB, 14382268416 bytes, 28090368 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 /dev/mapper/centos-swap: 1719 MB, 1719664640 bytes, 3358720 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes3.虚拟机中刷新scsi
ls /sys/class/scsi_disk/
0:0:0:0
echo 1 >/sys/class/scsi_disk/0\:0\:0\:0/device/rescan4.再使用fdisk -l命令查看磁盘，发现空间磁盘变大了。
[root@kafka1 ~]# ls /sys/class/scsi_disk/
0:0:0:0
[root@kafka1 ~]# echo 1 >/sys/class/scsi_disk/0\:0\:0\:0/device/rescan
[root@kafka1 ~]# fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x000aa121
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
Disk /dev/mapper/centos-root: 14.4 GB, 14382268416 bytes, 28090368 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 /dev/mapper/centos-swap: 1719 MB, 1719664640 bytes, 3358720 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes4. 使用命令 fdisk /dev/sda 对磁盘进行可用空间分区。
[root@kafka1 ~]# fdisk /dev/sda
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x000aa121
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
Command (m for help): n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): p
Partition number (3,4, default 3):
First sector (33554432-62914559, default 33554432):
Using default value 33554432
Last sector, +sectors or +size{K,M,G} (33554432-62914559, default 62914559):
Using default value 62914559
Partition 3 of type Linux and of size 14 GiB is set
Command (m for help): p
Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x000aa121
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
/dev/sda3 33554432 62914559 14680064 83 Linux
Command (m for help): t
Partition number (1-3, default 3): 3
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'
Command (m for help): p
Disk /dev/sda: 32.2 GB, 32212254720 bytes, 62914560 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: 0x000aa121
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
/dev/sda3 33554432 62914559 14680064 8e Linux LVM
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.注意，这里我用t命令将分区code改成8e,用于inux分区LVM类型。
5.将我们新加的分区进行初始化。
[root@kafka1 ~]# pvcreate /dev/sda3
Device /dev/sda3 not found.他会提示你设备不存在，刷一下。
[root@kafka1 ~]# partprobe -s
/dev/sda: msdos partitions 1 2 3
[root@kafka1 ~]# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created.6. 查看待扩容的VG名称 pvdisplay
[root@kafka1 ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda2
VG Name centos
PV Size <15.00 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 3839
Free PE 0
Allocated PE 3839
PV UUID RYNzEm-V9M9-OdZr-PZli-asfp-D78n-ozCvmF7.扩容
vgextend VG_NAME DEVICE
lvextend -r -l +100%FREE /dev/mapper/centos-root
[root@kafka1 ~]# vgextend centos /dev/sda3
Volume group "centos" successfully extended
[root@kafka1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 908M 0 908M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.9M 911M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/mapper/centos-root 14G 2.8G 11G 21% /
/dev/sda1 1014M 182M 833M 18% /boot
tmpfs 184M 0 184M 0% /run/user/0
[root@kafka1 ~]# lvextend -r -l +100%FREE /dev/mapper/centos-root
Size of logical volume centos/root changed from 13.39 GiB (3429 extents) to 27.39 GiB (7012 extents).
Logical volume centos/root successfully resized.
meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=877824 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=3511296, 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 3511296 to 7180288
[root@kafka1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 908M 0 908M 0% /dev
tmpfs 920M 0 920M 0% /dev/shm
tmpfs 920M 8.9M 911M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/mapper/centos-root 28G 2.8G 25G 11% /
/dev/sda1 1014M 182M 833M 18% /boot
tmpfs 184M 0 184M 0% /run/user/0扩容完成！
参考资料：
https://www.jianshu.com/p/537e8e8360af
https://www.programminghunter.com/article/2697297287/
https://echochio.pixnet.net/blog/post/44944759-esxi-%E7%9A%84-centos7-extend-hdd