[root@XenSystem ~]# df -hal
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
5.7G 1.1G 4.4G 20% /
proc 0 0 0 – /proc
sysfs 0 0 0 – /sys
devpts 0 0 0 – /dev/pts
/dev/xvda1 99M 27M 67M 29% /boot
tmpfs 257M 0 257M 0% /dev/shm
none 0 0 0 – /proc/sys/fs/binfmt_misc
sunrpc 0 0 0 – /var/lib/nfs/rpc_pipefs

[root@XenSystem~]# free -m
total       used       free     shared    buffers     cached
Mem:           512        506          5          0        447          9
-/+ buffers/cache:         49        463
Swap:         2079          0       2079

Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/xvdb doesn’t contain a valid partition table
Disk /dev/xvda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1          13      104391   83  Linux
/dev/xvda2              14        1044     8281507+  8e  Linux LVM

[root@XenSystem ~]# fdisk /dev/xvdb
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.

The number of cylinders for this disk is set to 2871.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

#输入n，新建分区
Command (m for help): n

#输入P，主分区
Command action
e   extended
p   primary partition (1-4)
p

#目前是xvdb第一个分区输入1
Partition number (1-4): 1

#敲回车，默认就行了
First cylinder (1-2871, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-2871, default 2871):
Using default value 2871

#这里输入t，指定分区的格式为8e (LVM)
Command (m for help): t 
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

#这里输入w，保存退出
Command (m for help): w 
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.

[root@XenSystem]# fdisk -l
Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvdb1 1 2871 23061276 8e Linux LVM

Disk /dev/xvda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/xvda1 * 1 13 104391 83 Linux
/dev/xvda2 14 1044 8281507+ 8e Linux LVM

[root@XenSystem ~]# vgs
VG #PV #LV #SN Attr VSize VFree
VolGroup00 2 2 0 wz–n- 49.84G 0

[root@XenSystem~]# pvcreate /dev/xvdb1
Physical volume “/dev/xvdb1” successfully created
[root@XenSystem~]# vgextend VolGroup00 /dev/xvdb1
Volume group “VolGroup00” successfully extended

[root@XenSystem~]# vgdisplay
— Volume group —
VG Name               VolGroup00
System ID
Format                lvm2
Metadata Areas        2
Metadata Sequence No  4
VG Access             read/write
VG Status             resizable
MAX LV                0
Cur LV                2
Open LV               2
Max PV                0
Cur PV                2
Act PV                2
VG Size               29.84 GB
PE Size               32.00 MB
Total PE              955
Alloc PE / Size       252 / 7.88 GB
Free  PE / Size       703 / 21.97 GB
VG UUID               jWlke0-R01B-RqBP-Qp1X-xxi0-ltOI-FompAt

[root@XenSystem~]# lvresize -L +21.96G /dev/VolGroup00/LogVol00
Rounding up size to full physical extent 21.97 GB
Extending logical volume LogVol00 to 27.81 GB
Logical volume LogVol00 successfully resized
[root@XenSystem~]# resize2fs /dev/VolGroup00/LogVol00
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/VolGroup00/LogVol00 is mounted on /; on-line resizing require d
Performing an on-line resize of /dev/VolGroup00/LogVol00 to 7290880 (4k) blocks.
The filesystem on /dev/VolGroup00/LogVol00 is now 7290880 blocks long.

[root@XenSystem~]# df -hal
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
27G 1.1G 25G 5% /
proc 0 0 0 – /proc
sysfs 0 0 0 – /sys
devpts 0 0 0 – /dev/pts
/dev/xvda1 99M 27M 67M 29% /boot
tmpfs 257M 0 257M 0% /dev/shm
none 0 0 0 – /proc/sys/fs/binfmt_misc
sunrpc 0 0 0 – /var/lib/nfs/rpc_pipefs

————————————完结———————————————–

系统重装后的重装扩展处理！

重装后，直接执行resize2fs进去动态扩容即可。

resize2fs /dev/VolGroup00/LogVol00

PVs missing导致LVM无法重新扩容的解决办法!

运行vgextend、vgdisplay返回错误：

Couldn’t find device with uuid ************************

Cannot change VG VolGroup00 while PVs are missing.
此时可以运行

vgreduce VolGroup00  –removemissing

然后重新扩容LVM即可