LVM是 Logical Volume Manager(邏輯卷管理)的簡寫。LVM將一個或多個硬盤的分區在邏輯上集合，相當於一個大硬盤來使用，當硬盤的空間不夠使用的時候，可以繼續將其它的硬盤的分區加入其中，這樣可以實現磁盤空間的動態管理，相對於普通的磁盤分區有很大的靈活性。
與傳統的磁盤與分區相比，LVM為計算機提供了更高層次的磁盤存儲。它使系統管理員可以更方便的為應用與用戶分配存儲空間。在LVM管理下的存儲卷可以按需要隨時改變大小與移除(可能需對文件系統工具進行升級)。LVM也允許按用戶組對存儲卷進行管理，允許管理員用更直觀的名稱(如"sales'、 'development')代替物理磁盤名(如'sda'、'sdb')來標識存儲卷。
物理存儲介質（The physical media）：這裡指系統的存儲設備：硬盤，如：/dev/hda1、/dev/sda等等，是存儲系統最低層的存儲單元。
物理卷（physical volume）：物理卷就是指硬盤分區或從邏輯上與磁盤分區具有同樣功能的設備(如RAID)，是LVM的基本存儲邏輯塊，但和基本的物理存儲介質（如分區、磁盤等）比較，卻包含有與LVM相關的管理參數。
卷組（Volume Group）：LVM卷組類似於非LVM系統中的物理硬盤，其由物理卷組成。可以在卷組上創建一個或多個“LVM分區”（邏輯卷），LVM卷組由一個或多個物理卷組成。
邏輯卷（logical volume）：LVM的邏輯卷類似於非LVM系統中的硬盤分區，在邏輯卷之上可以建立文件系統(比如/home或者/usr等)。
PE（physical extent）：每一個物理卷被劃分為稱為PE(Physical Extents)的基本單元，具有唯一編號的PE是可以被LVM尋址的最小單元。PE的大小是可配置的，默認為4MB。
LE（logical extent）：邏輯卷也被劃分為被稱為LE(Logical Extents) 的可被尋址的基本單位。在同一個卷組中，LE的大小和PE是相同的，並且一一對應。
簡單來說就是：
PV:是物理的磁盤分區
VG:LVM中的物理的磁盤分區，也就是PV，必須加入VG，可以將VG理解為一個倉庫或者是幾個大的硬盤。
LV：也就是從VG中劃分的邏輯分區
[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 、增加三個分區的操作（/dev/sdb1 /dev/sdb2 /dev/sdb3）
創建第一個主分區/dev/sdb1 大小為10G，/dev/sdb 為20G，/dev/sdb3 為10G
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p ##分區類型
Partition number (1-4): 1 ##第一個主分區
First cylinder (1-6527, default 1):
Using default value 1 ##起始塊
Last cylinder, +cylinders or +size{K,M,G} (1-6527, default 6527): +10G ##指定分區的大小Command (m for help): n ##開始分第二主分區
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 ##開始分第三個主分區
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 ##最後記得保存，寫入分區表
The partition table has been altered!
[root@localhost ~]# pvcreate /dev/sdb1 /dev/sdb2 /dev/sdb3 Physical volume "/dev/sdb1" successfully created #同時將三個分區創建成三個物理卷 Physical volume "/dev/sdb2" successfully created Physical volume "/dev/sdb3" successfully created
創建兩個卷組vg_server1 vg_server2 將物理卷/dev/sdb1、/dev/sdb2加入卷組vg_server1 ;將物理卷/dev/sdb3加入卷組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 ~]#
分在卷組vg_server1和vg_server2創建邏輯卷
[root@localhost ~]# lvcreate -L 15G -n vg_server1_lvm1 vg_server1 # -L指定卷大小，-n 指定邏輯卷名 Logical volume "vg_server1_lvm1" created. #指定跟卷組名 [root@localhost ~]# [root@localhost ~]# [root@localhost ~]# lvcreate -L 5G -n vg_server2_lvm2 vg_server2 Logical volume "vg_server2_lvm2" created.
[root@localhost ~]# lvdisplay #查看生成的邏輯卷 --- 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
[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)
文件系統標簽=
操作系統:Linux
塊大小=4096 (log=2)
分塊大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
983040 inodes, 3932160 blocks
196608 blocks (5.00%) reserved for the super user
第一個數據塊=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
正在寫入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)
文件系統標簽=
操作系統:Linux
塊大小=4096 (log=2)
分塊大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310720 blocks
65536 blocks (5.00%) reserved for the super user
第一個數據塊=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
正在寫入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 創建兩個目錄/mnt/lvm1 /mnt/lvm2，掛載生成兩個邏輯卷
[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
# # /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 擴容
LVM擴展，可以將另一個分區（沒有數據的分區）或另一塊新硬盤重新分區，然後將該分區創建物理卷，加入相應要擴容的邏輯卷的所在卷組。
在虛擬機添加一個塊硬盤。
[root@localhost dir]# fdisk /dev/sdc #給新加硬分區
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 ##新建的分區/dev/sdc2，將用於LVM擴容[root@localhost dir]# pvcreate /dev/sdc2 #將分區/dev/sdc2創建為物理卷
Physical volume "/dev/sdc2" successfully created
[root@localhost dir]# vgextend vg_server1 /dev/sdc2 #將物理卷/dev/sdc2 加入卷組vg_server1
Volume group "vg_server1" successfully extended
[root@localhost dir]# lvextend -L +5G /dev/vg_server1/vg_server1_lvm1 /dev/sdc2 #擴容/dev/vg_server1/vg_server1_lvm1邏輯卷，其中-L指定大小
#+5G 容量增加5G ,如果沒有”+“ 表示擴展到多少
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 #最後記得用命令resize 擴展邏輯大小
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]#
