Linux下LVM添加磁盘实践操作

LVM是 Logical Volume Manager(逻辑卷管理)的简写，它是Linux环境下对磁盘分区进行管理的一种机制，它由Heinz Mauelshagen在Linux 2.4内核上实现，目前最新版本为：稳定版1.0.5，开发版 1.1.0-rc2，以及LVM2开发版。

LVM是建立在硬盘和分区之上的一个逻辑层，来提高磁盘分区管理的灵活性

可以看一下lvm的示意图

每个磁盘可以分成多个分区，每个分区相当于一个pv，将pv化分成vg，在vg的基础上创建逻辑分区lv，逻辑分区lv上创建操作系统的文件系统。注意boot需要直接建到物理分区上去的。

RedHat默认情况下是安装lvm包的。

检测操作系统是否安装了lvm

[root@rac3 ~]# rpm -qa |grep lvm
system-config-lvm-1.1.4-1.3.el4
lvm2-2.02.42-5.el4

在支持热插拔的服务器上安装一块硬盘。

先用partprobe扫描是否有新的磁盘在用fdisk -l查看磁盘，我安装的磁盘就是最后一个

Disk /dev/sdg: 1073 MB, 1073741824 bytes

[root@rac3 ~]# partprobe
[root@rac3 ~]# fdisk -l

Disk /dev/sda: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14         140     1020127+  8e  Linux LVM
/dev/sda3             141        1305     9357862+  8e  Linux LVM

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1          37      297171   83  Linux
/dev/sdb2              38          74      297202+  83  Linux
/dev/sdb3              75         561     3911827+  83  Linux
/dev/sdb4             562        1305     5976180   83  Linux

Disk /dev/sdc: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1         130     1044193+  83  Linux

Disk /dev/sdd: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1               1         130     1044193+  83  Linux

Disk /dev/sde: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1               1         522     4192933+  83  Linux

Disk /dev/sdf: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdf1               1         522     4192933+  8e  Linux LVM

Disk /dev/sdg: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdg doesn’t contain a valid partition table

1、先对磁盘进行分区格式化

[root@rac3 ~]# fdisk /dev/sdg
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won’t be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1 
First cylinder (1-130, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-130, default 130):
Using default value 130

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

2、创建pv，

如果想将整个磁盘创建成一个物理卷，用下面，

[root@rac3 ~]# pvcreate /dev/sdg
  Physical volume “/dev/sdg” successfully created

也可以将当个分区创建成一个物理卷

[root@rac3 ~]# pvcreate /dev/sdg1
  Physical volume “/dev/sdg1” successfully created

查看所有的pv

[root@rac3 ~]# pvscan
  PV /dev/sda2   VG VolGroup00      lvm2 [992.00 MB / 0    free]
  PV /dev/sda3   VG VolGroup00      lvm2 [8.91 GB / 0    free]
  PV /dev/sdf1   VG VolGroup00      lvm2 [3.97 GB / 0    free]
  PV /dev/sdg                       lvm2 [1.00 GB]
  PV /dev/sdg1                      lvm2 [1019.72 MB]
  Total: 5 [15.84 GB] / in use: 3 [13.84 GB] / in no VG: 2 [2.00 GB]

查看物理卷组

[root@rac3 ~]# vgscan
  Reading all physical volumes.  This may take a while…
  Found volume group “VolGroup00” using metadata type lvm2

可以看到目前只有一个物理卷组

可以将新添加的物理卷添加到这个物理卷组中

[root@rac3 ~]# vgextend VolGroup00 /dev/sdg1
  Volume group “VolGroup00” successfully extended

查看已经有的lv

[root@rac3 ~]# lvscan
  ACTIVE            ‘/dev/VolGroup00/LogVol01’ [12.88 GB] inherit
  ACTIVE            ‘/dev/VolGroup00/LogVol00’ [992.00 MB] inherit

可以看到刚才扩展的VolGroup00上创建了两个lv

扩展系统文件占用的那个lv /dev/VolGroup00/LogVol01

在扩展的时候先看看vg空闲空间

— Volume group —
  VG Name               VolGroup00
  System ID            
  Format                lvm2
  Metadata Areas        4
  Metadata Sequence No  8
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                4
  Act PV                4
  VG Size               14.81 GB
  PE Size               32.00 MB
  Total PE              474
  Alloc PE / Size       474 / 14.81 GB
  Free  PE / Size       0 / 0                –这里显示vg的空余空间
  VG UUID               RC2l2s-SAFG-IeDh-qKiT-wDwf-bDfj-DGBoKo

扩展lv

[root@rac3 ~]# lvresize -L +0.96G /dev/VolGroup00/LogVol01
  Rounding up size to full physical extent 992.00 MB
  Extending logical volume LogVol01 to 13.84 GB
  Logical volume LogVol01 successfully resized

这时候需要在线重建lv

[root@rac3 ~]# ext2online /dev/mapper/VolGroup00-LogVol01

查看文件系统已经添加上去了，/dev/mapper/VolGroup00-LogVol01多了1G的空间

[root@rac3 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol01
                       14G  7.9G  5.2G  61% /
/dev/sda1              99M   14M   81M  14% /boot
none                  196M     0  196M   0% /dev/shm
/dev/sdc1            1020M  145M  875M  15% /ocr
/dev/sdd1            1020M  147M  873M  15% /votingdisk