Linux系统下对硬盘分区进行扩容的方法总结

硬盘快满了，加硬盘扩容，不管是独立的服务器，还是云空间新买的硬盘，扩容方式一样。下面以阿里VPS为例，详细说一下，挂载硬盘扩容的2种方法。
阿里VPS，个人觉得有以下二个方面需要改进
1，默认不是lvm，所以系统盘/dev/xvda1是不能扩容的，所以如果有大数据的东西，一开始就要考虑到扩容的问题。数据量越大，操作风险越大。
2，不能实现无缝扩容，也就是说，在后台扩容一下，不用登录到VPS，进行调整。非专业人士，扩容困难
一，不采用lvm，直接将硬盘挂载到目录
1，查看硬盘分区情况

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda120641404 14778400 481448076% /
tmpfs 5093000509300 0% /dev/shm

[root@iZ94zz3wqciZ ~]# fdisk -l

Disk /dev/xvda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x00078f9c

Device BootStart EndBlocks IdSystem
/dev/xvda1 * 1261120970496 83Linux //id是83，非lvm

Disk /dev/xvdb: 23.6 GB, 23622320128 bytes //新买的硬盘
255 heads, 56 sectors/track, 3230 cylinders
Units = cylinders of 14280 * 512 = 7311360 bytes
Sector size （logical/physical）: 512 bytes / 512 bytes
I/O size （minimum/optimal）: 512 bytes / 512 bytes
Disk identifier: 0x27cc1f5a

2，硬盘分区并查看分区情况

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# fdisk -S 56 /dev/xvdb//分区

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）: n //输入n
Command action
e extended
p primary partition （1-4）
p//主分区
Partition number （1-4）: 1 //分区号1
First cylinder （1-3230, default 1）:
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} （1-3230, default 3230）:
Using default value 3230

Command （m for help）: wq //保存并退出
The partition table has been altered！

[root@iZ94zz3wqciZ ~]# fdisk -l

Disk /dev/xvda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x00078f9c

Device BootStart EndBlocks IdSystem
/dev/xvda1 * 1261120970496 83Linux

Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 56 sectors/track, 3230 cylinders
Units = cylinders of 14280 * 512 = 7311360 bytes
Sector size （logical/physical）: 512 bytes / 512 bytes
I/O size （minimum/optimal）: 512 bytes / 512 bytes
Disk identifier: 0x27cc1f5a

Device BootStart EndBlocks IdSystem
/dev/xvdb1 1323023062172 83Linux//分区后

3，格式化新分区xvdb1

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# mkfs.ext4 /dev/xvdb1 //格式化分区
mke2fs 1.41.12 （17-May-2010）
Filesystem label=
OS type: Linux
Block size=4096 （log=2）
Fragment size=4096 （log=2）
Stride=0 blocks, Stripe width=0 blocks
1441792 inodes, 5765543 blocks
288277 blocks （5.00%） reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
176 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000

Writing inode tables: done
Creating journal （32768 blocks）: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 35 mounts or
180 days, whichever comes first.Use tune2fs -c or -i to override.

4，创建目录，并挂载分区

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# mkdir /mnt/fastdfs//挂载目录
[root@iZ94zz3wqciZ ~]# echo "/dev/xvdb1/mnt/fastdfsext4defaults0 0" >> /etc/fstab //重启会自动挂载
[root@iZ94zz3wqciZ ~]# mount -a//挂载所有目录

[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda120641404 14778404 481447676% /
tmpfs 5093000509300 0% /dev/shm
/dev/xvdb122694396 17606421365516 1% /mnt/fastdfs//新的分区已挂载

到这儿，就把一块独立的硬盘加到系统当中了。这种扩容的方式操作简单，但是扩展性不强，不推荐这种扩容方式。
二，采用lvm的方式，进行硬盘扩容（推荐）
1，取消前面测试的挂载，并删除分区

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# umount -a //取消挂载

[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdb //分区

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）: d //删除分区
Selected partition 1

Command （m for help）: wq //保存
The partition table has been altered！

2，安装lvm

复制代码代码如下:
[root@iZ94zz3wqciZ nginx]# uname -a //查看内核信息
Linux iZ94zz3wqciZ 2.6.32-431.23.3.el6.x86_64 #1 SMP Thu Jul 31 17:20:51 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

[root@iZ94zz3wqciZ ~]# yum install lvm2 device-mapper //安装 LVM2，2.6.9以后版本不用装device-mapper

[root@iZ94zz3wqciZ nginx]# lsmod | grep dm_mod//是否加载了dm_mod
dm_mod 843375 dm_mirror,dm_log

lvm的安装,首先加载device-mapper模块，从linux内核2.6.9开始，device-mapper模块就已经包含在内，所以你只需加载即可。加载mapper模块：modprobe dm_mod。
3，创建lvm分区

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdb //分区

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）: l

0Empty 24NEC DOS 81Minix / old Lin bfSolaris
1FAT12 39Plan 982Linux swap / So c1DRDOS/sec （FAT-
2XENIX root3cPartitionMagic83Linux c4DRDOS/sec （FAT-
3XENIX usr 40Venix 80286 84OS/2 hidden C:c6DRDOS/sec （FAT-
4FAT16 <32M41PPC PReP Boot 85Linux extendedc7Syrinx
5Extended42SFS 86NTFS volume set daNon-FS data
6FAT16 4dQNX4.x87NTFS volume set dbCP/M / CTOS / .
7HPFS/NTFS 4eQNX4.x 2nd part 88Linux plaintext deDell Utility
8AIX 4fQNX4.x 3rd part 8eLinux LVM dfBootIt
9AIX bootable50OnTrack DM93Amoebae1DOS access
aOS/2 Boot Manag 51OnTrack DM6 Aux 94Amoeba BBTe3DOS R/O
bW95 FAT32 52CP/M9fBSD/OSe4SpeedStor
cW95 FAT32 （LBA） 53OnTrack DM6 Aux a0IBM Thinkpad hi ebBeOS fs
eW95 FAT16 （LBA） 54OnTrackDM6a5FreeBSD eeGPT
fW95 Ext"d （LBA） 55EZ-Drivea6OpenBSD efEFI （FAT-12/16/
10OPUS56Golden Bowa7NeXTSTEPf0Linux/PA-RISC b
11Hidden FAT125cPriam Edisk a8Darwin UFSf1SpeedStor
12Compaq diagnost 61SpeedStor a9NetBSDf4SpeedStor
14Hidden FAT16 <3 63GNU HURD or Sys abDarwin boot f2DOS secondary
16Hidden FAT1664Novell NetwareafHFS / HFS+fbVMware VMFS
17Hidden HPFS/NTF 65Novell Netwareb7BSDI fs fcVMware VMKCORE
18AST SmartSleep70DiskSecure Mult b8BSDI swap fdLinux raid auto
1bHidden W95 FAT3 75PC/IX bbBoot Wizard hid feLANstep
1cHidden W95 FAT3 80Old Minix beSolaris bootffBBT
1eHidden W95 FAT1

Command （m for help）: n
Command action
e extended
p primary partition （1-4）
p
Partition number （1-4）: 1
First cylinder （1-2871, default 1）:
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} （1-2871, default 2871）:
Using default value 2871

Command （m for help）: p

Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 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: 0x27cc1f5a

Device BootStart EndBlocks IdSystem
/dev/xvdb1 1287123061276 83Linux//不是lvm分区格式

Command （m for help）: t//转换
Selected partition 1
Hex code （type L to list codes）: 8e //换成8e
Changed system type of partition 1 to 8e （Linux LVM）

Command （m for help）: p

Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 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: 0x27cc1f5a

Device BootStart EndBlocks IdSystem
/dev/xvdb1 1287123061276 8eLinux LVM //现在lvm分区格式了

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

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

4，创建逻辑卷组，以及逻辑卷等

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# pvcreate /dev/xvdb1 //创建物理卷
Physical volume "/dev/xvdb1" successfully created

[root@iZ94zz3wqciZ ~]# vgcreate myfiles /dev/xvdb1//创建逻辑卷组
Volume group "myfiles" successfully created

[root@iZ94zz3wqciZ ~]# vgchange -ay myfiles //激活逻辑卷组
0 logical volume（s） in volume group "myfiles" now active

[root@iZ94zz3wqciZ ~]# vgdisplay myfiles | grep "Total PE"//查看该卷组所有的PE
Total PE5629

[root@iZ94zz3wqciZ ~]# lvcreate -l 5629 -n fastdfs myfiles//创建逻辑卷
Logical volume "fastdfs" created.

5，格式化逻辑卷

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# mkfs.ext4 /dev/myfiles/fastdfs//格式化逻辑卷
mke2fs 1.41.12 （17-May-2010）
Filesystem label=
OS type: Linux
Block size=4096 （log=2）
Fragment size=4096 （log=2）
Stride=0 blocks, Stripe width=0 blocks
1441792 inodes, 5764096 blocks
288204 blocks （5.00%） reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
176 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000

Writing inode tables: done
Creating journal （32768 blocks）: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first.Use tune2fs -c or -i to override.

6,设置自动挂载，并查看分区

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# echo "/dev/myfiles/fastdfs /mnt/fastdfsext4defaults0 0" >> /etc/fstab //自动挂载
[root@iZ94zz3wqciZ ~]# mount -a //手动挂载
[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda120641404 14778608 481427276% /
tmpfs 5093000509300 0% /dev/shm
/dev/mapper/myfiles-fastdfs
22694396 17606421365516 1% /mnt/fastdfs //lvm逻辑卷已挂载

[root@iZ94zz3wqciZ ~]# reboot //操作完最好重启一下

7，再扩容一块硬盘到已有逻辑卷

复制代码代码如下:
[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdc //详细过程同上，就不详细说明了

[root@iZ94zz3wqciZ ~]# reboot

[root@iZ94zz3wqciZ ~]# pvcreate /dev/xvdc1 //创建物理卷
Physical volume "/dev/xvdc1" successfully created

[root@iZ94zz3wqciZ ~]# vgextend myfiles /dev/xvdc1//将新硬盘加入卷组
Volume group "myfiles" successfully extended

[root@iZ94zz3wqciZ ~]# vgdisplay myfiles | grep "Total PE"//查看所有PE
Total PE6907

[root@iZ94zz3wqciZ ~]# lvresize -l 6907 /dev/myfiles/fastdfs//重新规定大小
Size of logical volume myfiles/fastdfs changed from 21.99 GiB （5629 extents） to 26.98 GiB （6907 extents）.
Logical volume fastdfs successfully resized

[root@iZ94zz3wqciZ ~]# resize2fs /dev/myfiles/fastdfs//重新规定大小
resize2fs 1.41.12 （17-May-2010）
Filesystem at /dev/myfiles/fastdfs is mounted on /mnt/fastdfs; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 2
Performing an on-line resize of /dev/myfiles/fastdfs to 7072768 （4k） blocks.
The filesystem on /dev/myfiles/fastdfs is now 7072768 blocks long.

[root@iZ94zz3wqciZ ~]# df -h
FilesystemSizeUsed Avail Use% Mounted on
/dev/xvda1 20G 15G4.6G76% /
tmpfs 498M 0498M 0% /dev/shm
/dev/mapper/myfiles-fastdfs
27G172M 26G 1% /mnt/fastdfs //新的5G硬盘加上去了

如果是频繁的扩容硬盘的话，LVM是首选，扩展真的很方便。