linux虚拟机添加新硬盘

一直以来对VG都不是很理解，不过这次有人逼一下，就顺便好好理解一下。

其实现在如果是服务器,基本上架的时候,硬盘就是配置好，基本没啥机会添加硬盘，不过对于虚拟机，这样的机会还是很多的。

在Openstack下，给虚拟机添加一块硬盘倒是比较简单，不过有时候你会发现你添加的硬盘，虚拟机必须重启才能发现这块硬盘，现在终于有办法，不需要重启就可以找到硬盘。

运行这个脚本就可以 用http://www.garloff.de/kurt/linux/rescan-scsi-bus.sh

运行就可以。

这个时候，你通过

fdisk –l

就可以看到新增加的硬盘。应该是 /dev/sdb

第二磁盘格式化为LVM分区

[root@example1 ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xebb1f38a.
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 4 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): 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): 1
First cylinder (1-10240, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-10240, default 10240): 
Using default value 10240

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)

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

Calling ioctl() to re-read partition table.
Syncing disks.
[root@example1 ~]# fdisk -l

Disk /dev/sda: 21.5 GB, 21474836480 bytes
64 heads, 32 sectors/track, 20480 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x8e290e00

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           2           5        4096   41  PPC PReP Boot
Partition 1 does not end on cylinder boundary.
/dev/sda2               6         505      512000   83  Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3             506       20480    20454400   8e  Linux LVM
Partition 3 does not end on cylinder boundary.

Disk /dev/mapper/VolGroup-lv_root: 16.7 GB, 16747855872 bytes
255 heads, 63 sectors/track, 2036 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 4194 MB, 4194304000 bytes
255 heads, 63 sectors/track, 509 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xebb1f38a

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       10240    10485744   8e  Linux LVM

创建PV

pvcreate /dev/sdb1

查看当前的VG情况

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               19.50 GiB
  PE Size               4.00 MiB
  Total PE              4993
  Alloc PE / Size       4993 / 19.50 GiB
  Free  PE / Size       0 / 0   
  VG UUID               9qJAbQ-G6No-EO6b-3Rjk-0JMa-8plQ-wyMLBl

扩展VG

# vgextend VolGroup /dev/sdb1
  Volume group "VolGroup" successfully extended

查看VG

# vgdisplay
  --- Volume group ---
  VG Name               VolGroup
  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               29.50 GiB
  PE Size               4.00 MiB
  Total PE              7552
  Alloc PE / Size       4993 / 19.50 GiB
  Free  PE / Size       2559 / 10.00 GiB
  VG UUID               9qJAbQ-G6No-EO6b-3Rjk-0JMa-8plQ-wyMLBl

扩展LV

# lvextend -L +9G /dev/VolGroup/lv_root /dev/sdb1
  Extending logical volume lv_root to 24.60 GiB
  Logical volume lv_root successfully resized

认出分区

# resize2fs /dev/mapper/VolGroup-lv_root 
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 6448128 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_root is now 6448128 blocks long.

查看磁盘状况

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       25G  1.8G   22G   8% /
tmpfs                 233M     0  233M   0% /dev/shm
/dev/sda2             485M   44M  416M  10% /boot