LVM———Logical Volume Manager(逻辑卷管理器)的简写。LVM可以帮助我们为应用与用户方便地分配存储空间。在LVM管理下的逻辑卷可以按需改变大小或添加移除。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(如'sda','sdb')来标识存储卷。

传统分区概念
LVM逻辑卷管理
磁盘空间独立性 不能充分利用，尤其是一个FS只能对应一个分区 多磁盘PV组成存储池VG，再根据应用细分逻辑卷LV，空间利用率提高
空间扩展性 重新分区 采取静态或动态在线扩展卷组容量
数据备份 业务繁忙时，I/O接口读写频繁 可采取快照方式捕捉某一逻辑卷的瞬间精确拷贝已完成在线备份工作
用户使用性 分区标识无法满足大量用户要求 可根据用户需求定义lv逻辑卷的卷标

一、创建LVM的准备工作
1.搭建环境：OS:RHEL5.3
LVM包
IDE磁盘/dev/hdb(1024MB),/dev/hdd(1024MB)
2.转换磁盘分区——>lvm卷分区
最终方案：/dev/hdb ——> 创建 /dev/hdb1(Id:5,System:Extended)
/dev/hdb5(Id:8e,System:Linux LVM)
/dev/hdd ——> 创建 /dev/hdd1(Id:5,System:Extended)
/dev/hdd5(Id:8e,System:Linux LVM)
操作：(仅以/dev/hdb为例)


#fdisk /dev/hdb
#p(显示分区情况)——>#n(新建分区)——>#e(创建扩展分区)——>#l(创建逻辑分区)
#此处为实验环境方便后面的增减操作，所以我们将/dev/hdb全部划分为一个分区
#t(设置磁盘Hex code)——>#8e(LinuxLVM)——>#w(保存操作)
#p
Disk /dev/hdb: 1073 MB, 1073741824 bytes
16 heads, 63 sectors/track, 2080 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Device Boot Start End Blocks Id System
/dev/hdb1 1 2080 1048288+ 5 Extended
/dev/hdb5 1 2080 1048257 8e Linux LVM
#partprobe (此命令让kernel会重新读取磁盘分区表，修改生效)

二、创建LVM
1.创建PV盘
方案： /dev/hdb ——> lvm2[1024MB]
/dev/hdd ——> lvm2[1024MB]
操作:

#pvcreate /dev/hdb5 /dev/hdd5
#pvscan
#pvdisplay
"/dev/hdb5" is a new physical volume of "1023.69 MB"
--- NEW Physical volume ---
PV Name /dev/hdb5
VG Name
PV Size 1023.69 MB
Allocatable NO
PE Size (KByte) 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID zM7103-SJg4-ZjOb-BeL0-dlR1-HHh6-HCG8kG
"/dev/hdd5" is a new physical volume of "1023.69 MB"
--- NEW Physical volume ---
PV Name /dev/hdd5
VG Name
PV Size 1023.69 MB
Allocatable NO
PE Size (KByte) 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID hAk1Dx-QulA-YV4G-p8wa-7sWw-FiaC-10GorS

2.创建VG存储池
方案： lvm2(/dev/hdb)——> vg1
lvm2(/dev/hdd)——> vg2
操作：

#vgcreate vg1 /dev/hdb5
#vgcreate vg2 /dev/hdd5
#vgscan
#vgdisplay
--- Volume group ---
VG Name vg2
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1020.00 MB
PE Size 4.00 MB
Total PE 255
Alloc PE / Size 0 / 0
Free PE / Size 255 / 1020.00 MB
VG UUID Wa4Jo8-k3xY-BTng-uV6j-0Ee1-Vp8b-fNVrhQ
--- Volume group ---
VG Name vg1
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1020.00 MB
PE Size 4.00 MB
Total PE 255
Alloc PE / Size 0 / 0
Free PE / Size 255 / 1020.00 MB
VG UUID UGjfZd-shth-ZRTU-sVVm-MD0s-wzVB-zd7Uwt

3.分配LV逻辑卷
方案： work(/dev/hdb5)——> vg1
Study(/dev/hdd5)——> vg2
操作：

#lvcreate –L 500M –n work vg1
#lvcreate –L 500M –n study vg2
#lvscan
#lvdisplay
--- Logical volume ---
LV Name /dev/vg2/study
VG Name vg2
LV UUID 53VT9v-dyp0-lSST-eDFz-w2Ns-Os0Z-ERnqVU
LV Write Access read/write
LV Status available
# open 0
LV Size 500.00 MB
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Logical volume ---
LV Name /dev/vg1/work
VG Name vg1
LV UUID lhgKVg-hi95-W9gw-wOkZ-uyuy-BgZp-RrsCcA
LV Write Access read/write
LV Status available
# open 0
LV Size 500.00 MB
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0

4.分区格式化

#mkfs.ext3 /dev/vg1/work //或 #mkfs -j /dev/vg1/work
#mkfs.ext3 /dev/vg2/study //...
#df –l

Disk /dev/hda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 32 257008+ 83 Linux
/dev/hda2 33 97 522112+ 83 Linux
/dev/hda3 98 358 2096482+ 83 Linux
/dev/hda4 359 1044 5510295 5 Extended
/dev/hda5 359 549 1534176 83 Linux
/dev/hda6 550 848 2401686 83 Linux
/dev/hda7 849 913 522081 82 Linux swap / Solaris
/dev/hda8 914 978 522081 83 Linux
/dev/hda9 979 1043 522081 83 Linux

Disk /dev/hdb: 1073 MB, 1073741824 bytes
16 heads, 63 sectors/track, 2080 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes

Device Boot Start End Blocks Id System
/dev/hdb1 1 2080 1048288+ 5 Extended
/dev/hdb5 1 2080 1048257 8e Linux LVM

Disk /dev/hdd: 1073 MB, 1073741824 bytes
16 heads, 63 sectors/track, 2080 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes

Device Boot Start End Blocks Id System
/dev/hdd1 1 2080 1048288+ 5 Extended
/dev/hdd5 1 2080 1048257 8e Linux LVM

5.挂载新分区


#mkdir ../home/work ../home/study
#mount ../dev/vg1/work ../home/work
#mount ../dev/vg2/study ../home/study
#df –Th

Filesystem Type Size Used Avail Use% Mounted on
/dev/hda2 ext3 494M 212M 257M 46% /
/dev/hda9 ext3 494M 45M 425M 10% /var
/dev/hda8 ext3 494M 11M 458M 3% /opt
/dev/hda6 ext3 2.3G 68M 2.1G 4% /home
/dev/hda3 ext3 2.0G 1.7G 182M 91% /usr
/dev/hda5 ext3 1.5G 35M 1.4G 3% /usr/local
/dev/hda1 ext3 244M 12M 219M 6% /boot
tmpfs tmpfs 125M 0 125M 0% /dev/shm

/dev/mapper/vg1-work
ext3 485M 11M 449M 3% /home/work
/dev/mapper/vg2-study
ext3 485M 11M 449M 3% /home/study