LVM 的使用，谁都不能不保证服务器没有扩容的一天！而一旦到了扩容的那天，你才来找扩容方法是多么的失败！网上使用方法这么多，不如看Candy的图形操作，手把手教你扩容！还在等什么？现在收藏Candy的这篇文章，以后扩容不用求人。
VM环境：
操作系统：Centos 6.7 x86_64
CPU： x5650
内存：4G
硬盘：20G + 4TB
分区：
（别问Candy 为什么不定义SWAP）
这时候，我们假设服务器已经有如下东西：
1、安装好了Parted（yum install parted）
2、分区容量已经告捷，公司为服务器增加了一块4T硬盘用来增加容量！
3、除了/boot分区外，其余都为LVM 模式的扩展逻辑分区
1、软件安装与信息查看
首先查看软件是否安装：
[root@Candy ~]# rpm -qa | grep lvm
lvm2-libs-2.02.118-2.el6.x86_64
lvm2-2.02.118-2.el6.x86_64
[root@Candy ~]# lv
lvchange lvextend lvmdiskscan lvmsar lvresize
lvconvert lvm lvmdump lvreduce lvs
lvcreate lvmchange lvmetad lvremove lvscan
lvdisplay lvmconf lvmsadc lvrename
[root@Candy ~]# rpm -qa | grep parted
parted-2.1-29.el6.x86_64
好的，软件准备好了！顺便查看下 VM 硬件。
[root@Candy ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_candy-root
7.3G 231M 6.7G 4% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 477M 30M 422M 7% /boot
/dev/mapper/vg_candy-home
3.9G 8.0M 3.7G 1% /home
/dev/mapper/vg_candy-usr
3.9G 382M 3.3G 11% /usr
/dev/mapper/vg_candy-var
3.9G 63M 3.6G 2% /var
[root@Candy ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x0006e71c
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 2611 20458496 8e Linux LVM
Disk /dev/sdb: 4398.0 GB, 4398046511104 bytes
255 heads, 63 sectors/track, 534698 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: 0x00000000
Disk /dev/mapper/vg_candy-root: 8061 MB, 8061452288 bytes
255 heads, 63 sectors/track, 980 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: 0x00000000
Disk /dev/mapper/vg_candy-usr: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 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: 0x00000000
Disk /dev/mapper/vg_candy-var: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 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: 0x00000000
Disk /dev/mapper/vg_candy-home: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 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: 0x00000000
[root@Candy ~]# ls /dev/sd*
/dev/sda /dev/sda1 /dev/sda2 /dev/sdb
这时候我们看到，Centos 已经知道有个sdb的盘了，但是没挂载，没分区。
2、使用Parted进行扩容前的分区
现在假设1，除了/boot 其余分区都满了！ 这时候我们先来分区，讲4T的硬盘用上（/dev/sdb）。
[root@Candy ~]# parted /dev/sdb
GNU Parted 2.1
使用 /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel
新的磁盘标签类型？ gpt
(parted) mkpart
分区名称？ []?
文件系统类型？ [ext2]? ext4
起始点？ 0T
结束点？ 4T
(parted) p
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 4398GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name 标志
1 1049kB 4398GB 4398GB
(parted)set 1 lvm on
(parted)p
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 4398GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name 标志
1 1049kB 4398GB 4398GB lvm
(parted)q
[root@Candy ~]# ls /dev/sd*
/dev/sda /dev/sda1 /dev/sda2 /dev/sdb /dev/sdb1
现在让我们来解释一下操作：
1、mklabel将磁盘转换为gpt分区，因为MBR分区无法支持TB级硬盘（具体请自行查阅，parted当然也支持TB级以下的操作）
2、mkpart将转换好的gpt磁盘进行分区，需要提供文件系统类型、开始点、结束点。
3、输入p 打印出刚才才做后生成的分区。
4、set 1 lvm on 是将num为1的分区，tager设置为LVM ，这样才能添加到vm卷组里
下一步，我们查看我们的LVM组名叫什么。
[root@Candy ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg_candy 1 4 0 wz--n- 19.51g 0
[root@Candy ~]# vgdisplay
--- Volume group ---
VG Name vg_candy
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 5
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 1
Act PV 1
VG Size 19.51 GiB
PE Size 4.00 MiB
Total PE 4994
Alloc PE / Size 4994 / 19.51 GiB
Free PE / Size 0 / 0
VG UUID Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
[root@Candy ~]# lvscan
ACTIVE '/dev/vg_candy/usr' [4.00 GiB] inherit
ACTIVE '/dev/vg_candy/var' [4.00 GiB] inherit
ACTIVE '/dev/vg_candy/home' [4.00 GiB] inherit
ACTIVE '/dev/vg_candy/root' [7.51 GiB] inherit
[root@Candy ~]#
知道lvm卷组叫 'vg_candy'了，我们就使用vgextend来向lvm 'vg_candy' 卷组添加成员了。
[root@Candy ~]# vgextend vag_candy /dev/sdb1
Physical volume "/dev/sdb1" successfully created
Volume group "vg_candy" successfully extended
现在我们再用vgs命令看一下pv个数
[root@Candy ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg_candy 2 4 0 wz--n- 4.02t 4.00t
大家对比未添加时的vgs是否有看到，PV个数从1变为2了！现在让我们用vgdisplay看看现在分区的容量。
[root@Candy ~]# vgdisplay
--- Volume group ---
VG Name vg_candy
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 6
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 2
Act PV 2
VG Size 4.02 TiB
PE Size 4.00 MiB
Total PE 1053569
Alloc PE / Size 4994 / 19.51 GiB
Free PE / Size 1048575 / 4.00 TiB
VG UUID Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
再次对比未添加的vgdiplay命令发现，FreePE 的value 从 0 / 0 变为 1048575 / 4.00 TiB . 这样说明Candy已经成功将4TB的lvm 分区添加进入到vg_candy 逻辑卷组里了。
现在我们对所有逻辑分区进行扩容前，df -h 看看有哪些分区。
[root@Candy ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_candy-root 7.3G 231M 6.7G 4% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 477M 30M 422M 7% /boot
/dev/mapper/vg_candy-home 3.9G 8.0M 3.7G 1% /home
/dev/mapper/vg_candy-usr 3.9G 382M 3.3G 11% /usr
/dev/mapper/vg_candy-var 3.9G 63M 3.6G 2% /var
#这个排版比较乱，因为LVM卷组名太长了！为了方便大家查看，Candy手动给大家调整了排版！赞一个吧？
麻烦的事已经做完了，现在就剩下给各个分区添加容量了吧！
3、为磁盘进行扩容
现在最后一次假设，
假设：/ 、/home 、/usr 、/var 都需要添加500G 。
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-root
Size of logical volume vg_candy/root changed from 7.51 GiB (1922 extents) to 507.51 GiB (129922 extents).
Logical volume root successfully resized
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-home
Size of logical volume vg_candy/home changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
Logical volume home successfully resized
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-usr
Size of logical volume vg_candy/usr changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
Logical volume usr successfully resized
[root@Candy ~]# lvextend -L +500G /dev/mapper/vg_candy-var
Size of logical volume vg_candy/var changed from 4.00 GiB (1024 extents) to 504.00 GiB (129024 extents).
Logical volume var successfully resized
#大家注意，这一步操作时不可逆的！如果不小心打错分区名字还好！ 如果打错分区了，就得重复N遍来缩容，比较麻烦哦！建议大家注意看上面的FileSystem .. 切记切记....
提示扩容成功！ 让我们再次用上述命令查看LVM信息
[root@Candy ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg_candy 2 4 0 wz--n- 4.02t 2.05t
[root@Candy ~]# lvscan
ACTIVE '/dev/vg_candy/usr' [504.00 GiB] inherit
ACTIVE '/dev/vg_candy/var' [504.00 GiB] inherit
ACTIVE '/dev/vg_candy/home' [504.00 GiB] inherit
ACTIVE '/dev/vg_candy/root' [507.51 GiB] inherit
[root@Candy ~]# vgdisplay
--- Volume group ---
VG Name vg_candy
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 10
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 4
Open LV 4
Max PV 0
Cur PV 2
Act PV 2
VG Size 4.02 TiB
PE Size 4.00 MiB
Total PE 1053569
Alloc PE / Size 516994 / 1.97 TiB
Free PE / Size 536575 / 2.05 TiB
VG UUID Gcm5Ml-fc88-Xk5q-xuPC-Kj7Y-alfK-i770Gc
[root@Candy ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_candy-root 7.3G 231M 6.7G 4% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 477M 30M 422M 7% /boot
/dev/mapper/vg_candy-home 3.9G 8.0M 3.7G 1% /home
/dev/mapper/vg_candy-usr 3.9G 382M 3.3G 11% /usr
/dev/mapper/vg_candy-var 3.9G 63M 3.6G 2% /var
看到这里大家可能奇怪！为什么df -h 还没变呢？
4、刷新磁盘信息与写入
因为我们要用resize2fs 重设分区大小！ 这样才能使df -h 也能生效！而resize2fs 需要的时间与你给予的容量线性叠加！就是说，你给的容量越多，resize2fs 的需要的时间就越多。
[root@Candy ~]# resize2fs /dev//mapper/vg_candy-root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-root is mounted on /; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-root to 133040128 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-root is now 133040128 blocks long.
[root@Candy ~]# resize2fs /dev//mapper/vg_candy-usr
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-usr is mounted on /usr; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-usr to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-usr is now 132120576 blocks long.
[root@Candy ~]# resize2fs /dev//mapper/vg_candy-var
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-var is mounted on /var; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-var to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-var is now 132120576 blocks long.
[root@Candy ~]# resize2fs /dev//mapper/vg_candy-home
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev//mapper/vg_candy-home is mounted on /home; on-line resizing required old desc_blocks = 1, new_desc_blocks = 32
Performing an on-line resize of /dev//mapper/vg_candy-home to 132120576 (4k) blocks.
The filesystem on /dev//mapper/vg_candy-home is now 132120576 blocks long.
#当然有些人也喜欢partprobe这个命令，这个看个人吧！（关于这2个命令的区别，个人去搜索吧！）
[root@Candy ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_candy-root 500G 245M 474G 1% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 477M 30M 422M 7% /boot
/dev/mapper/vg_candy-home 496G 16M 471G 1% /home
/dev/mapper/vg_candy-usr 496G 390M 471G 1% /usr
/dev/mapper/vg_candy-var 496G 71M 471G 1% /var
5、结束语
你什么都不用做而且可以重启了。顺便给大家晒一张Candy重启后系统自动挂载的图！
吐槽： Centos 系统还是比较聪明的！ 其实重启与不重启都能使用，Candy只是为大家演示重启后的效果！希望此文章能帮助大家平滑的进行水平扩容！