一、LVM简介
LVM是 Logical Volume Manager(逻辑卷管理)的简写。LVM将一个或多个硬盘的分区在逻辑上集合，相当于一个大硬盘来使用，当硬盘的空间不够使用的时候，可以继续将其它的硬盘的分区加入其中，这样可以实现磁盘空间的动态管理，相对于普通的磁盘分区有很大的灵活性。
与传统的磁盘与分区相比，LVM为计算机提供了更高层次的磁盘存储。它使系统管理员可以更方便的为应用与用户分配存储空间。在LVM管理下的存储卷可以按需要随时改变大小与移除(可能需对文件系统工具进行升级)。LVM也允许按用户组对存储卷进行管理，允许管理员用更直观的名称(如"sales'、 'development')代替物理磁盘名(如'sda'、'sdb')来标识存储卷。
二、 LVM基本术语
物理存储介质（The physical media）：这里指系统的存储设备：硬盘，如：/dev/hda1、/dev/sda等等，是存储系统最低层的存储单元。
物理卷（physical volume）：物理卷就是指硬盘分区或从逻辑上与磁盘分区具有同样功能的设备(如RAID)，是LVM的基本存储逻辑块，但和基本的物理存储介质（如分区、磁盘等）比较，却包含有与LVM相关的管理参数。
卷组（Volume Group）：LVM卷组类似于非LVM系统中的物理硬盘，其由物理卷组成。可以在卷组上创建一个或多个“LVM分区”（逻辑卷），LVM卷组由一个或多个物理卷组成。
逻辑卷（logical volume）：LVM的逻辑卷类似于非LVM系统中的硬盘分区，在逻辑卷之上可以建立文件系统(比如/home或者/usr等)。
PE（physical extent）：每一个物理卷被划分为称为PE(Physical Extents)的基本单元，具有唯一编号的PE是可以被LVM寻址的最小单元。PE的大小是可配置的，默认为4MB。
LE（logical extent）：逻辑卷也被划分为被称为LE(Logical Extents) 的可被寻址的基本单位。在同一个卷组中，LE的大小和PE是相同的，并且一一对应。
简单来说就是：
PV:是物理的磁盘分区
VG:LVM中的物理的磁盘分区，也就是PV，必须加入VG，可以将VG理解为一个仓库或者是几个大的硬盘。
LV：也就是从VG中划分的逻辑分区
三、创建和管理LVM
1、显示硬盘及所属分区情况
[root@localhost ~]# fdisk /dev/sdb
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): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 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: 0x44817895
Device Boot Start End Blocks Id System
2 、增加三个分区的操作（/dev/sdb1 /dev/sdb2 /dev/sdb3）
创建第一个主分区/dev/sdb1 大小为10G，/dev/sdb 为20G，/dev/sdb3 为10G
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p ##分区类型
Partition number (1-4): 1 ##第一个主分区
First cylinder (1-6527, default 1):
Using default value 1 ##起始块
Last cylinder, +cylinders or +size{K,M,G} (1-6527, default 6527): +10G ##指定分区的大小
Command (m for help): n ##开始分第二主分区
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (1307-6527, default 1307):
Using default value 1307
Last cylinder, +cylinders or +size{K,M,G} (1307-6527, default 6527): +20G
Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 8e
Changed system type of partition 2 to 8e (Linux LVM)
Command (m for help): n ##开始分第三个主分区
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (3919-6527, default 3919):
Using default value 3919
Last cylinder, +cylinders or +size{K,M,G} (3919-6527, default 6527): +10G
Command (m for help): t
Partition number (1-4): 3
Hex code (type L to list codes): 8e
Changed system type of partition 3 to 8e (Linux LVM)
Command (m for help): p
Disk /dev/sdb: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 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: 0x44817895
Device Boot Start End Blocks Id System
/dev/sdb1 1 1306 10490413+ 8e Linux LVM
/dev/sdb2 1307 3918 20980890 8e Linux LVM
/dev/sdb3 3919 5224 10490445 8e Linux LVM
Command (m for help): w ##最后记得保存，写入分区表
The partition table has been altered!
3、创建物理卷PV
[root@localhost ~]# pvcreate /dev/sdb1 /dev/sdb2 /dev/sdb3
Physical volume "/dev/sdb1" successfully created #同时将三个分区创建成三个物理卷
Physical volume "/dev/sdb2" successfully created
Physical volume "/dev/sdb3" successfully created
4、创建卷组VG
创建两个卷组vg_server1 vg_server2 将物理卷/dev/sdb1、/dev/sdb2加入卷组vg_server1 ;将物理卷/dev/sdb3加入卷组vg_server2
[root@localhost ~]# vgcreate vg_server1 /dev/sdb1 /dev/sdb2
Volume group "vg_server1" successfully created
[root@localhost ~]#
[root@localhost ~]#
[root@localhost ~]# vgcreate vg_server2 /dev/sdb3
Volume group "vg_server2" successfully created
[root@localhost ~]#
5、创建逻辑卷lV
分在卷组vg_server1和vg_server2创建逻辑卷
[root@localhost ~]# lvcreate -L 15G -n vg_server1_lvm1 vg_server1 # -L指定卷大小，-n 指定逻辑卷名
Logical volume "vg_server1_lvm1" created. #指定跟卷组名
[root@localhost ~]#
[root@localhost ~]#
[root@localhost ~]# lvcreate -L 5G -n vg_server2_lvm2 vg_server2
Logical volume "vg_server2_lvm2" created.
[root@localhost ~]# lvdisplay #查看生成的逻辑卷
--- Logical volume ---
LV Path /dev/vg_server2/vg_server2_lvm2
LV Name vg_server2_lvm2
VG Name vg_server2
LV UUID jP8fZf-CR1l-Tpat-Q92Y-H4bZ-unJQ-dTYDra
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-04-14 00:21:11 +0800
LV Status available
# open 0
LV Size 5.00 GiB
Current LE 1280
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Logical volume ---
LV Path /dev/vg_server1/vg_server1_lvm1
LV Name vg_server1_lvm1
VG Name vg_server1
LV UUID j4UX2E-LuRf-WKgW-9KGH-dBb3-RvAK-PXcORB
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-04-14 00:20:54 +0800
LV Status available
# open 0
LV Size 15.00 GiB
Current LE 3840
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
6、格式化
[root@localhost ~]# mk2fs -t ext3 /dev/vg_server1/vg_server1_lvm1
-bash: mk2fs: command not found
[root@localhost ~]# mke2fs -t ext3 /dev/vg_server1/vg_server1_lvm1
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
983040 inodes, 3932160 blocks
196608 blocks (5.00%) reserved for the super user
第一个数据块=0
Maximum filesystem blocks=4026531840
120 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208
正在写入inode表: 完成
Creating journal (32768 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
This filesystem will be automatically checked every 20 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]# mke2fs -t ext3 /dev/vg_server2/vg_server2_lvm2
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310720 blocks
65536 blocks (5.00%) reserved for the super user
第一个数据块=0
Maximum filesystem blocks=1342177280
40 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736
正在写入inode表: 完成
Creating journal (32768 blocks): 完成
Writing superblocks and filesystem accounting information: 完成
This filesystem will be automatically checked every 37 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
7 创建两个目录/mnt/lvm1 /mnt/lvm2，挂载生成两个逻辑卷
[root@localhost vg_server1]# mount /dev/vg_server2/vg_server2_lvm2 /mnt/lvm2
[root@localhost vg_server1]# mount /dev/vg_server1/vg_server1_lvm1 /mnt/lvm1
8、写入开机自动挂载
#
# /etc/fstab
# Created by anaconda on Mon Sep 14 21:58:13 2015
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=5d9aa445-64de-4001-b45f-10db6bf51248 / ext4 defaults 1 1
UUID=c26e447c-8fde-4c82-b15f-5cd3a86a402b /boot ext4 defaults 1 2
UUID=ec4bd037-8b39-4148-9b07-9f15279caa92 swap swap defaults 0 0
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/mapper/vg_server1-lvm_1 /mnt/lvm1 ext3 defaults 0 0
/dev/mapper/vg_server2-lvm_2 /mnt/lvm2 ext3 defaults 0 0
~
9.LVM 扩容
LVM扩展，可以将另一个分区（没有数据的分区）或另一块新硬盘重新分区，然后将该分区创建物理卷，加入相应要扩容的逻辑卷的所在卷组。
在虚拟机添加一个块硬盘。
[root@localhost dir]# fdisk /dev/sdc #给新加硬分区
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): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (1307-2610, default 1307):
Using default value 1307
Last cylinder, +cylinders or +size{K,M,G} (1307-2610, default 2610): +5G
Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 8e
Changed system type of partition 2 to 8e (Linux LVM)
Command (m for help): p
Disk /dev/sdc: 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: 0xe4571f5c
Device Boot Start End Blocks Id System
/dev/sdc1 1 1306 10490413+ 8e Linux LVM
/dev/sdc2 1307 1960 5253255 8e Linux LVM ##新建的分区/dev/sdc2，将用于LVM扩容
[root@localhost dir]# pvcreate /dev/sdc2 #将分区/dev/sdc2创建为物理卷
Physical volume "/dev/sdc2" successfully created
[root@localhost dir]# vgextend vg_server1 /dev/sdc2 #将物理卷/dev/sdc2 加入卷组vg_server1
Volume group "vg_server1" successfully extended
[root@localhost dir]# lvextend -L +5G /dev/vg_server1/vg_server1_lvm1 /dev/sdc2 #扩容/dev/vg_server1/vg_server1_lvm1逻辑卷，其中-L指定大小
#+5G 容量增加5G ,如果没有”+“ 表示扩展到多少
Size of logical volume vg_server1/vg_server1_lvm1 changed from 15.00 GiB (3840 extents) to 20.00 GiB (5120 extents).
Logical volume vg_server1_lvm1 successfully resized
[root@localhost lvm1]# /sbin/resize2fs /dev/vg_server1/vg_server1_lvm1 #最后记得用命令resize 扩展逻辑大小
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_server1/vg_server1_lvm1 is mounted on /mnt/lvm1; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 2
Performing an on-line resize of /dev/vg_server1/vg_server1_lvm1 to 7340032 (4k) blocks.
The filesystem on /dev/vg_server1/vg_server1_lvm1 is now 7340032 blocks long.
[root@localhost lvm1]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 18G 3.7G 13G 22% /
tmpfs 504M 0 504M 0% /dev/shm
/dev/sda1 194M 26M 158M 15% /boot
/dev/mapper/vg_server2-vg_server2_lvm2 5.0G 139M 4.6G 3% /mnt/lvm2
/dev/mapper/vg_server1-vg_server1_lvm1 25G 173M 26G 1% /mnt/lvm1
[root@localhost lvm1]#
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