虚拟机磁盘扩容

在esx server上安装虚拟机时，由于只分配了默认的8GB磁盘空间。今天要在虚拟机RHEL5.2上安装Oracle RAC，空间不太够，所以在
虚拟机上把分配磁盘空间扩大的20GB。在esx server上扩容磁盘空间的方法很简单，在此不提，下面具体说说如何把该扩容的磁盘空间
在虚拟机上应用上去。

以下是未扩容前的状态：
[root@localhost ~]# fdisk -l

Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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        1044     8281507+  8e  Linux LVM
[root@localhost ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                      7.0G  4.8G  1.8G  73% /
/dev/sda1              99M   12M   82M  13% /boot
tmpfs                 187M     0  187M   0% /dev/shm
/dev/hdc              183M  183M     0 100% /media/VMware Tools
可以看到sda有21.4GB，但是只利用了sda1和sda2；根目录挂载在/dev/mapper/VolGroup00-LogVol00，我们要做的是，把sda上剩余的空间扩容到/dev/mapper/VolGroup00-LogVol00。

1）首先，通过fdisk /dev/sda命令将sda剩余空间创建一个分区：
[root@localhost ~]# fdisk /dev/sda

The number of cylinders for this disk is set to 2610.
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)

Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (1045-2610, default 1045):
Using default value 1045
Last cylinder or +size or +sizeM or +sizeK (1045-2610, default 2610):
Using default value 2610

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

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
[root@localhost ~]#

此时可以看到多了一个sda3的分区：
[root@localhost ~]# fdisk -l

Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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        1044     8281507+  8e  Linux LVM
/dev/sda3            1045        2610    12578895   83  Linux

此时查看了一下/dev下，不知道为何没有/dev/sda3，于是重启了一下虚拟机RHEL，重启完成后，出现了/dev/sda3.
一开始在这个地方折腾了一会，如果不重启，在利用命令pvcreate /dev/sda3创建pv时，总是提示Device /dev/sda3 not found (or ignored by filtering).

重启完成后，进入lvm模式，创建pv：
lvm> pvcreate /dev/sda3
  Physical volume "/dev/sda3" successfully created

扩容vg：
lvm> vgextend VolGroup00 /dev/sda3
  /dev/cdrom: open failed: Read-only file system
  Attempt to close device '/dev/cdrom' which is not open.
  Volume group "VolGroup00" successfully extended

把lv扩容到vg的剩余容量：
lvm> lvextend /dev/VolGroup00/LogVol00 /dev/sda3
  Extending logical volume LogVol01 to 12.72 GB
  Logical volume LogVol01 successfully resized

最后，通过resize2fs命令令新增的空间在线（on-line）生效：
[root@localhost dev]# resize2fs /dev/VolGroup00/LogVol00
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/VolGroup00/LogVol00 is mounted on /; on-line resizing required
Performing an on-line resize of /dev/VolGroup00/LogVol00 to 5005312 (4k) blocks.
The filesystem on /dev/VolGroup00/LogVol00 is now 5005312 blocks long.

效果如下：
[root@localhost dev]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       19G  4.8G   13G  28% /
/dev/sda1              99M   12M   82M  13% /boot
tmpfs                 187M     0  187M   0% /dev/shm
/dev/hdc              3.4G  3.4G     0 100% /media/RHEL_5.2 x86_64 DVD