CentOS根分区扩容方法

操作环境：

[root@linux ~]# uname -a

Linux linux 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@linux ~]# 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@linux ~]# 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@linux ~]#

第三步、添加第二块硬盘

查看此时系统磁盘情况

root@linux ~]# 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@linux ~]#

第四步、对第二块硬盘sdb进行分区

[root@linux ~]# 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't be recoverable.

Warning: invalid flag 0x0000 of partitiontable 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 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'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@linux ~]# 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@linux ~]# 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@linux ~]# 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@linux ~]# 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@linux ~]# vgextend VolGroup/dev/sdb4

Volume group "VolGroup" successfully extended

第十步、查看当前的逻辑卷

[root@linux ~]# 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@linux ~]# 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@linux ~]# 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@linux ~]# 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@linux ~]# 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@linux ~]# 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。