使用lvm进行分区管理

在我看来使用lvm的好处有两个：可以很方便地动态expand/shrink分区大小；不受分区个数的限制。
在howtoforge网站有非常好的lvm使用的介绍：http://www.howtoforge.com/linux_lvm
这里记录自己的操作过程：

1.使用pvcreate创建physical volumn
[root@jcwkyl ~]# fdisk -l

Disk /dev/sda: 320.0 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 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        6540   52428127+  83  Linux
/dev/sda3           6541       13067   52428127+  83  Linux
/dev/sda4          13068       38913  207607995   8e  Linux LVM
[root@jcwkyl ~]# pvcreate /dev/sda4
  Physical volume "/dev/sda4" successfully created

2.使用vgcreate创建volumn group
[root@jcwkyl ~]# vgcreate xen_space /dev/sda4
  Volume group "xen_space" successfully created

3.使用lvcreate创建logical volumn
[root@jcwkyl ~]# lvcreate -n image_pool -L 100G xen_space
  Logical volume "image_pool" created
[root@jcwkyl ~]# lvcreate -n swap -L 5G xen_space
  Logical volume "swap" created

4.在新创建的logical volumn上创建文件系统，并挂载使用
[root@jcwkyl ~]# mkfs.ext3 /dev/xen_space/image_pool
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
13107200 inodes, 26214400 blocks
1310720 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=0
800 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872

Writinginode tables:done                           
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 27 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@jcwkyl ~]# mount /dev/xen_space/image_pool /vm
在/etc/fstab中加入下面一条记录，使得每次开机时自动mount相应的分区：
/dev/xen_space/image_pool/vm                  ext3   defaults        0 0