CentOS6.5增加挂载点容量

一.背景：因为公司虚拟机 （/） 目录容量过小，导致一些任务不能正常执行，需要给虚拟机扩容

二.操作：

　初始磁盘情况：　　

　1.使用 df 命令查看磁盘与目录的容量：

[root@shaonian ~]# df -h
Filesystem                    Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root   48G   22G   25G  % /
tmpfs                         .8G       .8G   % /dev/shm
/dev/xvda1                    485M   33M  427M   % /boot
/dev/mapper/VolGroup-lv_home  .7G  138M  .4G   % /home
cm_processes                  .8G  808K  .8G   % /var/run/cloudera-scm-agent/process

　2.使用 fdisk -l 命令查看磁盘分区：

[root@shaonian ~]# fdisk -l

Disk /dev/xvdb: 85.9 GB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00000000

Disk /dev/xvda: 64.4 GB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x000e9377

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *                                Linux
Partition  does not end on cylinder boundary.
/dev/xvda2                             8e  Linux LVM

Disk /dev/xvdd:  MB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_root: 52.3 GB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap:  MB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_home:  MB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0x00000000

发现执行 fdisk -l 显示的第一行，显示出的 /dev/xvdb 分区，并没有被使用。这就是是管理人员分出给磁盘扩容用的磁盘空间，我们接下来要用这个分区为（/）目录扩容

3.接着执行 fdisk /dev/xvdb ，进入 fdisk 命令行给磁盘分区

[root@shaonian ~]# fdisk /dev/xvdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xd259beb1.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table  will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p

Disk /dev/xvdb: 85.9 GB,  bytes
 heads,  sectors/track,  cylinders
Units = cylinders of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk identifier: 0xd259beb1

    Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (-)
p
Partition number (-):
First cylinder (-, default ):
Using default value
Last cylinder, +cylinders or +size{K,M,G} (-, default ):
Using default value 

Command (m for help): t
Selected partition
Hex code (type L to list codes): 8e
Changed system type of partition  to 8e (Linux LVM)

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

Calling ioctl() to re-read partition table.
Syncing disks.

可以看出，输入fdisk /dev/xvdb  命令后，提示我们输入命令，我们依次输入以下命令：

p 查看已有分区，由于这个分区是新的，所以为空

n 新建分区：

　　p 新建主分区

1 输入分区号，因为之前没有分区，所以这是第一个分区，分区号为1

接下来 First cylinder 和 Last cylinder 我们直接点击回车，默认使用全部空间

t 改变分区类型

8e 改变分区类型为 LVM

w 写入改变

此时系统将改变分区，然后退出 fdisk 命令行。如果没有自动退出，输入 q 退出。

4. 用 mkfs 命令对分区进行格式化

mkfs -t ext3 /dev/xvdb1

此时将进入漫长的等待......

5.添加 LVM到原来的 LVM组

lvm　　进入lvm管理

lvm> pvcreate /dev/xvdb1　　创建虚拟分区

lvm> vgextend VolGroup  /dev/xvdb1　　把刚刚创建的分区添加到虚拟分区组

lvm>lvextend -L +79.5 /dev/mapper/VolGroup-lv_root　　扩展容量（可以看到 /dev/mapper/VolGroup-lv_root）就是我们执行 df -h 时 （/）目录的文件系统）

lvm> quit　　退出

6. 文件系统扩容

resize2fs /dev/mapper/VolGroup-lv_root

至此，扩容全部完成，此时再次执行 df -h :

[root@shaonian ~]# df -h
Filesystem                    Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root  127G   22G   99G  % /
tmpfs                         .8G       .8G   % /dev/shm
/dev/xvda1                    485M   33M  427M   % /boot
/dev/mapper/VolGroup-lv_home  .7G  138M  .4G   % /home
cm_processes                  .8G  792K  .8G   % /var/run/cloudera-scm-agent/process

可以看到 （/）目录的容量大大增加了

PS:顺便一提，一共扩容了三台虚拟机，其中两台都是很顺利的，有一台不知道什么原因（可能是其中某一步操作错误），在执行

lvm> vgextend VolGroup /dev/mapper/Group-lv_root

操作时，出现了如下错误：

Couldn't find device with uuid cRdLUx-1ttO-JUKw-K2Bu-FOw2-EIrk-87Xdl3.

运行 pvscan 查看 pv：

lvm> pvscan
  Couldn't find device with uuid cRdLUx-1ttO-JUKw-K2Bu-FOw2-EIrk-87Xdl3.
  Couldn't find device with uuid 7Ef30A-6qRY-bBP0-CTH9-f6ut-kE8x-ch4c2j.
  PV /dev/xvda2       VG VolGroup   lvm2 [59.51 GiB /     free]
  PV unknown device   VG VolGroup   lvm2 [80.00 GiB / 80.00 GiB free]
  PV unknown device   VG VolGroup   lvm2 [80.00 GiB / 80.00 GiB free]
  PV /dev/xvdb4       VG VolGroup   lvm2 [80.00 GiB / 80.00 GiB free]
  Total:  [299.50 GiB] / in use:  [299.50 GiB] / in no VG:  [   ]

发现 有两行 出现了 unknown device

执行

lvm> vgreduce --removemissing  VolGroup

即可。