LVM逻辑卷管理（下）
LVM相比较于传统分区其优势在于可以动态扩大缩小分区大小。
扩容vg
[root@lvm ~]# pvcreate /dev/sdg
Physical volume "/dev/sdg" successfully created
[root@lvm ~]# pvcreate /dev/sdh
Physical volume "/dev/sdh" successfully created
[root@lvm ~]# vgextend photo /dev/sd[gh]
/dev/cdrom: open failed: 只读文件系统
/dev/cdrom: open failed: 只读文件系统
Attempt to close device '/dev/cdrom' which is not open.
Volume group "photo" successfully extended
给photo 这个vg扩容，增加了2个pv进来
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扩容lv
[root@lvm 7yue5]# lvextend -L +20G /dev/photo/7yue5 扩容20G
/dev/cdrom: open failed: 只读文件系统
Extending logical volume 7yue5 to 40.00 GB
[root@lvm 7yue5]# resize2fs /dev/photo/7yue5 重新识别文件系统的大小
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/photo/7yue5 is mounted on /7yue5; on-line resizing required
Performing an on-line resize of /dev/photo/7yue5 to 10485760 (4k) blocks.
The filesystem on /dev/photo/7yue5 is now 10485760 blocks long.
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然后缩小分区与扩大相似，只是resize2fs和lvextend(vgextend)的顺序相反，即先用resize2fs，再用resize2fs。
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另外要注意的是不要再没关闭LVM的情况下关闭分区
正确的步骤是：
1.umonut卸载LVM文件系统
2.lvremove删除逻辑卷
3.vgremove删除卷组
4.pvremove删除物理卷
5.清除/etc/fstab中的LVM挂载记录
6.fdisk修改分区ID