LVM的基本应用、扩展及缩减实现

LVM : 

     Logical Volume Manager 逻辑卷管理， 它是一种能够用在Linux内核的逻辑分卷管理器，经常使用于管理磁盘和其余大型存储设备上。

LVM的应用：

             在生产环境中常见于增长磁盘，可将多个磁盘合理的合并成一个或多个，但又不会影响业务的进行。

与raid的区别：

              LVM是软件的卷管理方式，而RAID是磁盘保护的方法。对于重要的业务来讲，通常是同时存在。RAID用来保护物理的磁盘不会由于故障而中断业务。LVM用来实现对卷的良性的管理，更好的利用磁盘资源。

LVM的扩展及缩减实例： 

1，首先查看逻辑卷容量
[root@bogon ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       39G  461M   37G   2% /
/dev/mapper/VolGroup00-LogVol03
                       64G  222M   61G   1% /var
/dev/mapper/VolGroup00-LogVol02
                       49G  2.0G   45G   5% /usr
/dev/mapper/VolGroup00-LogVol01
                       39G  177M   37G   1% /home
/dev/sda1              99M   13M   82M  14% /boot
tmpfs                1005M     0 1005M   0% /dev/shm
/dev/hdc              3.5G  3.5G     0 100% /media

2，在home下有lost+found能够看到home分区单独挂载到一个分区下面
[root@bogon ~]# ls /home/
innofidei  lost+found

3，卸载并验证
[root@bogon ~]# umount /dev/mapper/VolGroup00-LogVol01 
[root@bogon ~]# ls /home/

4，resize2fs  卷组
[root@bogon ~]# resize2fs /dev/mapper/VolGroup00-LogVol01 20G 
resize2fs 1.39 (29-May-2006)
Resizing the filesystem on /dev/mapper/VolGroup00-LogVol01 to 5242880 (4k) blocks.
The filesystem on /dev/mapper/VolGroup00-LogVol01 is now 5242880 blocks long.
注意这里会提醒你e2fsck的
因此resize2fs以前要这样作： e2fsck -f /dev/mapper/VolGroup-logVol01

5，缩减lvm
[root@bogon ~]# lvreduce -L 20G /dev/mapper/VolGroup00-LogVol01
  /dev/hdc: open failed: Read-only file system
  WARNING: Reducing active logical volume to 20.00 GB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce LogVol01? [y/n]: y
  Reducing logical volume LogVol01 to 20.00 GB
  Logical volume LogVol01 successfully resized

6,从新挂载并验证
[root@bogon ~]# mount -a
[root@bogon ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       39G  461M   37G   2% /
/dev/mapper/VolGroup00-LogVol03
                       64G  222M   61G   1% /var
/dev/mapper/VolGroup00-LogVol02
                       49G  2.0G   45G   5% /usr
/dev/sda1              99M   13M   82M  14% /boot
tmpfs                1005M     0 1005M   0% /dev/shm
/dev/hdc              3.5G  3.5G     0 100% /media
/dev/mapper/VolGroup00-LogVol01
                       20G  173M   19G   1% /home
[root@bogon ~]# ls /home/
innofidei  lost+found

7，扩展另外一lvm
[root@bogon ~]# lvextend -L +20G /dev/mapper/VolGroup00-LogVol02
  /dev/hdc: open failed: Read-only file system
  Extending logical volume LogVol02 to 70.00 GB
  Logical volume LogVol02 successfully resized
[root@bogon ~]# resize2fs /dev/mapper/VolGroup00-LogVol02
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/mapper/VolGroup00-LogVol02 is mounted on /usr; on-line resizing required
Performing an on-line resize of /dev/mapper/VolGroup00-LogVol02 to 18350080 (4k) blocks.
The filesystem on /dev/mapper/VolGroup00-LogVol02 is now 18350080 blocks long.

8,再验证
[root@bogon ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       39G  461M   37G   2% /
/dev/mapper/VolGroup00-LogVol03
                       64G  222M   61G   1% /var
/dev/mapper/VolGroup00-LogVol02
                       68G  2.0G   63G   4% /usr
/dev/sda1              99M   13M   82M  14% /boot
tmpfs                1005M     0 1005M   0% /dev/shm
/dev/hdc              3.5G  3.5G     0 100% /media
/dev/mapper/VolGroup00-LogVol01
                       20G  173M   19G   1% /home