CentOS根分区扩容方法

操作环境：
[root@linuxidc ~]# uname -a
Linux linuxidc 2.6.32-358.18.1.el6.x86_64#1 SMP Wed Aug 28 17:19:38 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
现状分析：
系统有两个硬盘，第一个硬盘107G,“/”分区空间当时分区时只给了7.7G过小，空间马上占完。现在系统有第二个硬盘sdb大小为16GB，希望把sdb的所有空间加入到“/”分区中，是其空间容量从7.7GB变成7.7GB+16GB（约2.4GB）。（当然如果这里只有一个硬盘sda,有很多空间尚未使用可以进行同样的操作）
操作步骤如下：
第一步、查看本机现有分区情况
[root@linuxidc ~]# df -h
文件系统容量已用可用已用%% 挂载点
/dev/mapper/VolGroup-lv_root
                    7.7G  7.1G 155M  98% /
tmpfs                3.9G  296K 3.9G  1% /dev/shm
/dev/sda1            485M  64M 396M  14% /boot
/dev/sda3              83G  350M  79G  1% /media
第二步、查看本机的磁盘情况
[root@linuxidc ~]# fdisk -l

Disk /dev/sda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x000dc0ad

 Device Boot      Start        End      Blocks  Id  System
/dev/sda1  *          1          64      512000  83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64        2089  16264192  8e  Linux LVM
/dev/sda3            2090      13054  88076362+  83  Linux

Disk /dev/mapper/VolGroup-lv_root: 8325 MB,8325693440 bytes
255 heads, 63 sectors/track, 1012 cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 8325 MB,8325693440 bytes
255 heads, 63 sectors/track, 1012 cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x00000000
注意：此时还没有在EXSI5.0中添加第二块硬盘
[root@linuxidc ~]#
第三步、添加第二块硬盘

查看此时系统磁盘情况
root@linuxidc ~]# fdisk -l

Disk /dev/sda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x000dc0ad

 Device Boot      Start        End      Blocks  Id  System
/dev/sda1  *          1          64      512000  83  Linux
Partition 1 does not end on cylinderboundary.
/dev/sda2              64        2089  16264192  8e  Linux LVM
/dev/sda3            2090      13054  88076362+  83  Linux

Disk /dev/sdb: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_root: 8325 MB,8325693440 bytes
255 heads, 63 sectors/track, 1012 cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VolGroup-lv_swap: 8325 MB,8325693440 bytes
255 heads, 63 sectors/track, 1012 cylinders
Units = cylinders of 16065 * 512 = 8225280bytes
Sector size (logical/physical): 512 bytes /512 bytes
I/O size (minimum/optimal): 512 bytes / 512bytes
Disk identifier: 0x00000000

可以看到我们新添加的硬盘sdb

[root@linuxidc ~]#
第四步、对第二块硬盘sdb进行分区

[root@linuxidc ~]# fdisk /dev/sdb
Device contains neither a valid DOSpartition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with diskidentifier 0xfa4abbdc.
Changes will remain in memory only, untilyou decide to write them.
After that, of course, the previous contentwon&＃39;t be recoverable.

Warning: invalid flag 0x0000 of partitiontable 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated.It&＃39;s strongly recommended to
      switch off the mode (command &＃39;c&＃39;) and change display units to
      sectors (command &＃39;u&＃39;).

Command (m for help): m
Command action
 a  toggle a bootable flag
 b  edit bsd disklabel
 c  toggle the dos compatibilityflag
 d  delete a partition
 l  list known partition types
 m  print this menu
 n  add a new partition
 o  create a new empty DOSpartition table
 p  print the partition table
 q  quit without saving changes
 s  create a new empty Sundisklabel
 t  change a partition&＃39;s system id
 u  change display/entry units
 v  verify the partition table
 w  write table to disk and exit
 x  extra functionality (expertsonly)

Command (m for help): n
Command action
 e  extended
 p  primary partition (1-4)
p  
Partition number (1-4): 4
First cylinder (1-2088, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G}(1-2088, default 2088): 
Using default value 2088

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

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

说明：上面操作对sdb硬盘进行了分区操作，设为sdb4分区了（当然上面建立的主分区可以为1-4中的任意一个，我这里选择的4）。

第五步、对新建立的sdb4分区进行格式

[root@linuxidc ~]# mkfs.ext4 /dev/sdb4
mke2fs 1.41.12 (17-May-2010)
文件系统标签=
操作系统:Linux
块大小=4096 (log=2)
分块大小=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1048576 inodes, 4192957 blocks
209647 blocks (5.00%) reserved for thesuper user
第一个数据块=0
Maximum filesystem blocks=4294967296
128 block groups
32768 blocks per group, 32768 fragments pergroup
8192 inodes per group
Superblock backups stored on blocks: 
      32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
      4096000

正在写入inode表: 完成
Creating journal (32768 blocks): 完成
Writing superblocks and filesystemaccounting information: done完成

This filesystem will be automaticallychecked every 20 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

说明：将sdb4分区格式化为ext4格式，因为CentOS安装是系统的格式ext4，所以这里要注意一下。

第六步、格式后的sdb4分区添加为物理卷
[root@linuxidc ~]# pvcreate /dev/sdb4
Physical volume "/dev/sdb4" successfully created

第七步、查看当前系统的物理卷（PV）情况

[root@linuxidc ~]# pvdisplay
---Physical volume ---
PVName /dev/sda2
VGName VolGroup
PVSize 15.51 GiB / not usable3.00 MiB
Allocatable yes (butfull)
PESize 4.00 MiB
Total PE 3970
Free PE 0
Allocated PE 3970
PVUUID Up77sG-sNKf-Ja0k-crBf-N0wz-a5hy-T6sVFh

"/dev/sdb4" is a new physical volume of "15.99 GiB"
---NEW Physical volume ---
PVName /dev/sdb4
VGName 
PVSize 15.99 GiB
Allocatable NO
PESize 0 
Total PE 0
Free PE 0
Allocated PE 0
PVUUID Gqnw7N-HooX-S2Nz-1NIZ-YpOe-g0jo-grG1rQ 
说明：可以看到添加的新物理卷sdb4，大小都符合我们添加时的设置

第八步、查看当前卷组情况
[root@linuxidc ~]# vgdisplay
---Volume group ---
VGName VolGroup
System ID 
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VGAccess read/write
VGStatus resizable
MAXLV 0
CurLV 2
Open LV 2
MaxPV 0
CurPV 1
ActPV 1
VGSize 15.51 GiB
PESize 4.00 MiB
Total PE 3970
Alloc PE / Size 3970 / 15.51GiB
Free PE / Size 0 / 0 
VGUUID PPrifh-glzl-nnxX-YkBm-xJ1s-rgnw-d1WsJd

第九步、将分区sdb4转换为扩展分区

[root@linuxidc ~]# vgextend VolGroup/dev/sdb4
Volume group "VolGroup" successfully extended

第十步、查看当前的逻辑卷

[root@linuxidc ~]# lvdisplay
---Logical volume ---
LVPath /dev/VolGroup/lv_root
LVName lv_root
VGName VolGroup
LVUUID dCIsej-0NWX-bVFe-bT6L-c4eY-oy4G-9lNBOC
LVWrite Access read/write
LVCreation host, time , 
LVStatus available
#open 1
LVSize 7.75 GiB
Current LE 1985
Segments 1
Allocation inherit
Read ahead sectors auto
-currently set to 256
Block device 253:0

---Logical volume ---
LVPath /dev/VolGroup/lv_swap
LVName lv_swap
VGName VolGroup
LVUUID K5bxJo-2SmM-6NCU-mBJP-Qzp1-ZODH-nbLK0k
LVWrite Access read/write
LVCreation host, time , 
LVStatus available
#open 1
LVSize 7.75 GiB
Current LE 1985
Segments 1
Allocation inherit
Read ahead sectors auto
-currently set to 256
Block device 253:1

说明：这里可以看到“/”根分区的路径名称为：/dev/VolGroup/lv_root

第十一步、查看扩展后的卷组情况
[root@linuxidc ~]# vgdisplay
---Volume group ---
VGName VolGroup
System ID 
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VGAccess read/write
VGStatus resizable
MAXLV 0
CurLV 2
Open LV 2
MaxPV 0
CurPV 2
ActPV 2
VGSize 31.50 GiB
PESize 4.00 MiB
Total PE 8064
Alloc PE / Size 3970 / 15.51GiB
Free PE / Size 4094 / 15.99 GiB
VGUUID PPrifh-glzl-nnxX-YkBm-xJ1s-rgnw-d1WsJd
说明：扩展后的卷子情况，可以看出大小增加了16GB（与第八步中的对比）

第十二步、将新增的逻辑卷全部扩展到“/”分区中

[root@linuxidc ~]# lvextend -L +15.99G/dev/VolGroup/lv_root 
Rounding size to boundary between physical extents: 15.99 GiB
Extending logical volume lv_root to 23.75 GiB
Logical volume lv_root successfully resized

说明：这里sdb4总共有16G，所以把16BG全部添加给根分区。

第十三步、查看“/”根分区格式，并重新刷新根分区的大小
[root@linuxidc ~]# e2fsck -f/dev/VolGroup/lv_root 
e2fsck 1.41.12 (17-May-2010)
/dev/VolGroup/lv_root is mounted.
e2fsck: 无法继续, 中止.

[root@linuxidc ~]# resize2fs /dev/VolGroup/lv_root 
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/VolGroup/lv_root ismounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of/dev/VolGroup/lv_root to 6224896 (4k) blocks.
The filesystem on /dev/VolGroup/lv_root isnow 6224896 blocks long.
说明：命令resize2fs即刷新根分区“/dev/VolGroup/lv_root”的容量。

第十三步、查看刷新后根分区的大小

[root@linuxidc ~]# df -h
文件系统容量已用可用已用%% 挂载点
/dev/mapper/VolGroup-lv_root
24G 7.1G 16G 32% /
tmpfs 3.9G 144K 3.9G 1% /dev/shm
/dev/sda3 83G 350M 79G 1% /media/Lucene

说明：可以看到根分区的大小有7.7G变成了24G，重启一下系统再来看情况。此时就可以继续安装软件了，不会提示空间不足了。