3台虚拟机都是20G磁盘，用着用着发现不够了，先扩容了一台，各种百度...各种坑，每个人的情况不一样，发现不一样的地方最后立即百度查看。一台扩容成功后，打算再扩容一台，目的是留一个记录。（我是用xshell超级用户链接的的虚拟机）
扩容大致分为3步：1.外部设置；2.设置分区；3.重启；4挂载；（挂载过程中解决了物理卷、卷组、逻辑卷、格式化问题，如果挂载失败，则可以一次解决排除这些问题）
1.关闭虚拟机（不是挂起），点击“虚拟机/设置”，选择“硬盘”，扩容至40G
2.启动虚拟机，root用户进入linux系统，添加新的分区
2.1查看当前分区状况
[root@slave1 /root]$ fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000381a8
Device Boot Start End Blocks Id System
/dev/sda1 * 1 39 307200 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 39 2358 18631680 83 Linux
/dev/sda3 2358 2611 2031616 82 Linux swap / Solaris
当前最大分区为sda3，新创建的分区为sda4。（请留意加重部分）
2.2输入以下命令
[root@slave1 /root]$ fdisk /dev/sda
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): m #2.3命令行提示下输入【m】
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): n #输入命令【n】添加新分区
Command action
e extended
p primary partition (1-4)
p #输入命令【p】创建主分区。
Selected partition 4
First cylinder (2611-5221, default 2611): #回车
Using default value 2611
Last cylinder, +cylinders or +size{K,M,G} (2611-5221, default 5221): #回车
Using default value 5221
Command (m for help): w #输入【w】保存
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.
[root@slave1 /]$ mkdir disk4
[root@slave1 /]$ mount /dev/sda4 /disk4
mount: you must specify the filesystem type
挂载的时候发生了报错，看红色字体，原因可能是没有物理卷、卷组、逻辑卷、格式化引起的（4.1，4.2，4.3主要用于解决这3个问题）
4.1查看物理卷：
[root@slave1 /]$ pvs
没有输出！！！说明没有物理卷，创建的分区是sda4，这里为这个分区创建物理卷。
[root@slave1 /]$ pvcreate /dev/sda4
Physical volume "/dev/sda4" successfully created
此时再查看物理卷，ok
[root@slave1 /]$ pvs
PV VG Fmt Attr PSize PFree
/dev/sda4 lvm2 a-- .99g .99g
4.2查看卷组
[root@slave1 /]$ vgs
No volume groups found
报错，没有，先创建卷组vgdata
[root@slave1 /]$ vgcreate vgdata /dev/sda4
Volume group "vgdata" successfully created
再次查看卷组，OK！！！
[root@slave1 /]$ vgs
VG #PV #LV #SN Attr VSize VFree
vgdata wz--n- .99g .09g
[root@slave1 /]$ vgdisplay
--- Volume group ---
VG Name vgdata
System ID
Format lvm2
Metadata Areas
Metadata Sequence No
VG Access read/write
VG Status resizable
MAX LV
Cur LV
Open LV
Max PV
Cur PV
Act PV
VG Size 19.99 GiB
PE Size 4.00 MiB
Total PE
Alloc PE / Size / 4.90 GiB
Free PE / Size / 15.09 GiB
VG UUID f8keeP-x5yH-qdfd-9roM-hbAt-ALEI-yYG4wB
4.3查看逻辑卷
[root@slave1 /]$ lvdisplay
No volume groups found
报错，没有，创建逻辑卷
[root@slave1 /]$ lvcreate -L4.9G vgdata -n lvolhome /dev/sda4
Rounding up size to full physical extent 4.90 GiB
Logical volume "lvolhome" created
查看创建结果，OK!!!
[root@slave1 /]$ lvdisplay
--- Logical volume ---
LV Path /dev/vgdata/lvolhome
LV Name lvolhome
VG Name vgdata
LV UUID dI2lMQ-sayc-XGlG-xa9I-USfC-97kt-0Kbt6k
LV Write Access read/write
LV Creation host, time slave1, -- :: -
LV Status available
# open
LV Size 4.90 GiB
Current LE
Segments
Allocation inherit
Read ahead sectors auto
- currently set to
Block device :
4.4格式化磁盘
[root@slave1 /]$ mkfs.ext4 /dev/sda4
mke2fs 1.41.12 (17-May-2010)
/dev/sda4 is apparently in use by the system; will not make a filesystem here!
报错、手动移除DM管理
[root@slave1 /]$ dmsetup status
vgdata-lvolhome: linear
[root@slave1 /]$ dmsetup remove_all
[root@slave1 /]$ dmsetup status
No devices found
重新格式化，OK！！！
[root@slave1 /]$ mkfs.ext4 /dev/sda4
mke2fs 1.41. (-May-)
Filesystem label=
OS type: Linux
Block size= (log=)
Fragment size= (log=)
Stride= blocks, Stripe width= blocks
inodes, blocks
blocks (5.00%) reserved for the super user
First data block=
Maximum filesystem blocks=
block groups
blocks per group, fragments per group
inodes per group
Superblock backups stored on blocks:
, , , , , , , , , Writing inode tables: done
Creating journal ( blocks): done
Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every mounts or
days, whichever comes first. Use tune2fs -c or -i to override.
重新挂载，没有报错，mount成功，磁盘扩容成功
[root@slave1 /]$ mount /dev/sda4 /disk4
挂载前：
[root@slave1 /root]$ df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 18G .0G 14G % /
tmpfs 491M 72K 491M % /dev/shm
/dev/sda1 291M 34M 242M % /boot
挂载后：
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 18G .1G 14G % /
tmpfs 491M 72K 491M % /dev/shm
/dev/sda1 291M 34M 242M % /boot
/dev/sda4 20G 172M 19G % /disk4