lvm的创建

LVM概述

              LVM是逻辑盘卷管理（Logical Volume Manger)的简称，它是linux环境下对磁盘分区的一种简称，LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘管理的

灵活性。

              每个Linux使用者在安装Linux时都会遇到这样的困境：在为系统分区时，如何精确评估和分配各个硬盘分区的容量，因为系统管理员不但要考虑到当前某个分区需要的容量，还要预见该分区以后可能需要的容量的最大值。因为如果估 计不准确，当遇到某个分区不够用时管理员可能甚至要备份整个系统、清除硬盘、重新对硬盘分区，然后恢复数据到新分区。

             PV（Physical Volume,物理卷)

                              物理卷是LVM机制的基本存储设备，通常对应为一个普通分区。物理卷一般直接使用设备文件名，如dev/sda1.用于转换物理卷的普通分区

，需要用fdisk工具将分区类型的ID改为"8e"，即文件系统为LINUX LVM。

              VG（Volume Group,卷组)

                               卷组是由一个或多个物理卷组成的一个整体，在卷组中可以动态添加或移除物理卷，名称用户自由定义。

               LV（Logical Volume，逻辑卷)

                                 逻辑卷是建立在卷组之上，与物理卷没有直接关系。逻辑卷就是从卷组中切除的一小块空间，作为用户穿件文件系统基础。

使用格式化工具mkfs进行格式，即可挂载。

             LVM创建步骤

                  1.创建分区 类型为LINUX LVM

                  2.创建PV（PVSCAN 扫所有描物理卷 ,PVDISPLAY列出物理卷的详细信息）

          3.创建VG卷组

          4.创建LV卷

                [root@localhost ~]# fdisk /dev/sdb

                 e   extended
                         p   primary partition (1-4)
                              p
                            Partition number (1-4): 1
                            First cylinder (1-652, default 1): 
                            Using default value 1
                            Last cylinder, +cylinders or +size{K,M,G} (1-652, default 652): +100M  
                                t  改为8e

                     Command (m for help):p

                     Disk /dev/sdb: 5368 MB, 5368709120 bytes
                             255 heads, 63 sectors/track, 652 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: 0x9685cd1a

                          Device Boot      Start         End      Blocks   Id  System
                             /dev/sdb1               1          14      112423+  8e  Linux LVM
                            /dev/sdb2              15          53      313267+  8e  Linux LVM

[root@localhost Desktop]# partx /dev/sdb        ----刷新下 这样就不用重启
# 1:        63-   224909 (   224847 sectors,    115 MB)
# 2:    224910-   851444 (   626535 sectors,    320 MB)
# 3:         0-       -1 (        0 sectors,      0 MB)
# 4:         0-       -1 (        0 sectors,      0 MB)

[root@localhost Desktop]# pvcreate /dev/sdb1 /dev/sdb2
  Writing physical volume data to disk "/dev/sdb1"
  Physical volume "/dev/sdb1" successfully created
  Writing physical volume data to disk "/dev/sdb2"
  Physical volume "/dev/sdb2" successfully created

  "/dev/sdb1" is a new physical volume of "109.79 MiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name              
  PV Size               109.79 MiB
  Allocatable           NO
  PE Size               0  
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               QuU7x7-DrGw-XQyg-ojD0-vPhi-rPz6-exd5G6
  
  "/dev/sdb2" is a new physical volume of "305.93 MiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb2
  VG Name              
  PV Size               305.93 MiB
  Allocatable           NO
  PE Size               0  
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               mlZa19-uFoj-4ccj-eeKS-Pa4f-LRe2-UcYpms

[root@localhost Desktop]# vgcreate vg1 /dev/sdb1 /dev/sdb2         ----vg1为卷组名称，/dev/sdb1 和2 分配到VG1组里
  Volume group "vg1" successfully created

[root@localhost Desktop]# vgdisplay
  --- Volume group ---
  VG Name               vg1
  System ID            
  Format                lvm2
  Metadata Areas        2
  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                2
  Act PV                2
  VG Size               412.00 MiB
  PE Size               4.00 MiB
  Total PE              103
  Alloc PE / Size       0 / 0  
  Free  PE / Size       103 / 412.00 MiB
  VG UUID               Fmf8tO-TdiW-U3nB-ug0G-ny8x-eZHG-a50dWE

lvcreate -L 200M -n lv1 vg1  ---创建名为lv1 的卷
  Logical volume "lv1" created

进行格式化

mkfs.ext4 /dev/vg1/lv1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
51200 inodes, 204800 blocks
10240 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
25 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks:
 8193, 24577, 40961, 57345, 73729

Writing inode tables: done                           
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

然后Mount就可以了