最近想自己hack一下android的源代码, 可是发现代码好大啊, 编译一下大概需要40G的空闲空间. 而之前装好的Linux本来硬盘就只有40G, 于是研究了一下, 发现是可以直接扩容的, 虽然步骤有点麻烦.

备份数据

虽然说按照这个步骤做应该不会出什么问题, 但是重装系统毕竟是个麻烦事, 所以在扩容之前, 先做一下备份! 避免产生人品问题而后悔莫及. 毕竟备份虚拟机还是很省事的, 直接整个目录拷贝一份即可.

扩大VirtualDisk

我们先把VirtualBox里的这块硬盘扩大:

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C:
cd "C:\Program Files\Oracle\VirtualBox"
VBoxManage modifyhd "D:\VM\mint-xfce\mint-xfce.vdi" --resize 1000000

正常的话, 系统会输出:

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0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100% 然后就退出了.

我们可以去VirtualBox里看看硬盘大小:

已经变成1000G了(其实我不小心多打了1个0, 不过无所谓了).

在Linux中创建新的分区

进入Linux, 切换为root用户, 运行

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fdisk -l
:

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chi-VirtualBox ~ # fdisk -l

Disk /dev/sda: 1048.6 GB, 1048576000000 bytes
255 heads, 63 sectors/track, 127482 cylinders, total 2048000000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00067091

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      499711      248832   83  Linux
/dev/sda2          501758    83884031    41691137    5  Extended
/dev/sda5          501760    83884031    41691136   8e  Linux LVM

Disk /dev/mapper/mint--vg-root: 40.5 GB, 40542142464 bytes
255 heads, 63 sectors/track, 4928 cylinders, total 79183872 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/mint--vg-root doesn't contain a valid partition table

Disk /dev/mapper/mint--vg-swap_1: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders, total 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/mint--vg-swap_1 doesn't contain a valid partition table

可以看到, 虽然硬盘的大小已经扩大了, 但是分区表还是没变. 所以现在我们去创建一个新的分区. 在我的Linux Mint里面有图形化界面可以创建, 所以我就不用

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fdisk
了, 免得出错, 反正记得要 创建一个primary分区, 分区类型要选lvm(8e), 完成之后, 里面的分区应该是这样:

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chi-VirtualBox ~ # fdisk -l

Disk /dev/sda: 1048.6 GB, 1048576000000 bytes
255 heads, 63 sectors/track, 127482 cylinders, total 2048000000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00067091

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      499711      248832   83  Linux
/dev/sda2          501758    83884031    41691137    5  Extended
/dev/sda3        83886080  2047999999   982056960   8e  Linux LVM
/dev/sda5          501760    83884031    41691136   8e  Linux LVM

Disk /dev/mapper/mint--vg-root: 40.5 GB, 40542142464 bytes
255 heads, 63 sectors/track, 4928 cylinders, total 79183872 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/mint--vg-root doesn't contain a valid partition table

Disk /dev/mapper/mint--vg-swap_1: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders, total 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/mint--vg-swap_1 doesn't contain a valid partition table

其中

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/dev/sda3
是我们新创建的分区.

创建和扩展lvm分区

扩大volume group

由于使用了lvm, 我们可以方便的扩展已有分区. 首先查看已有的volume group:

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chi-VirtualBox ~ # vgdisplay 

--- Volume group ---
VG Name               mint-vg
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               39.76 GiB
PE Size               4.00 MiB
Total PE              10178
Alloc PE / Size       10178 / 39.76 GiB
Free  PE / Size       0 / 0   
VG UUID               aR8Gl4-toof-YxoL-Jo2L-X8it-wfEe-B1YxUF

可以看到, 已有一个volume group, 我们可以把

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/dev/sda3
加到这个volume group里面:

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chi-VirtualBox ~ # vgextend mint-vg /dev/sda3

No physical volume label read from /dev/sda3
Writing physical volume data to disk "/dev/sda3"
Physical volume "/dev/sda3" successfully created
Volume group "mint-vg" successfully extended

我们再看看volume group的情况:

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chi-VirtualBox ~ # vgdisplay 

--- Volume group ---
VG Name               mint-vg
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               976.32 GiB
PE Size               4.00 MiB
Total PE              249937
Alloc PE / Size       10178 / 39.76 GiB
Free  PE / Size       239759 / 936.56 GiB
VG UUID               aR8Gl4-toof-YxoL-Jo2L-X8it-wfEe-B1YxUF

可以看到, 原来的volume group已经被我们扩大到了

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976.32GB
.

扩大 logical volume

首先, 我们查看目前的logical Volume:

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chi-VirtualBox ~ # lvdisplay 

--- Logical volume ---
LV Path                /dev/mint-vg/root
LV Name                root
VG Name                mint-vg
LV UUID                2hNBQf-1zGs-3nZF-4feA-uR9W-WVDQ-32lLm4
LV Write Access        read/write
LV Creation host, time mint, 2013-07-23 09:26:24 +0800
LV Status              available
# open                 1
LV Size                37.76 GiB
Current LE             9666
Segments               1
Allocation             inherit
Read ahead sectors     auto
- currently set to     256
Block device           252:0

--- Logical volume ---
LV Path                /dev/mint-vg/swap_1
LV Name                swap_1
VG Name                mint-vg
LV UUID                fD6Mwy-IYEy-ZxXN-aPPW-WNn7-catg-o1bRsX
LV Write Access        read/write
LV Creation host, time mint, 2013-07-23 09:26:24 +0800
LV Status              available
# open                 2
LV Size                2.00 GiB
Current LE             512
Segments               1
Allocation             inherit
Read ahead sectors     auto
- currently set to     256
Block device           252:1

可以看到, 系统中只有一个logical Volume, 它是

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/root
的挂载点. 我们现在要做的就是将这个logical volume 扩大. 在logical volume扩大时, 会自动使用volume group中的空间.

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chi-VirtualBox ~ # lvextend -L 100G /dev/mint-vg/root
Extending logical volume root to 100.00 GiB
Logical volume root successfully resized

chi-VirtualBox ~ # lvdisplay 
--- Logical volume ---
LV Path                /dev/mint-vg/root
LV Name                root
VG Name                mint-vg
LV UUID                2hNBQf-1zGs-3nZF-4feA-uR9W-WVDQ-32lLm4
LV Write Access        read/write
LV Creation host, time mint, 2013-07-23 09:26:24 +0800
LV Status              available
# open                 1
LV Size                100.00 GiB
Current LE             25600
Segments               2
Allocation             inherit
Read ahead sectors     auto
- currently set to     256
Block device           252:0

--- Logical volume ---
LV Path                /dev/mint-vg/swap_1
LV Name                swap_1
VG Name                mint-vg
LV UUID                fD6Mwy-IYEy-ZxXN-aPPW-WNn7-catg-o1bRsX
LV Write Access        read/write
LV Creation host, time mint, 2013-07-23 09:26:24 +0800
LV Status              available
# open                 2
LV Size                2.00 GiB
Current LE             512
Segments               1
Allocation             inherit
Read ahead sectors     auto
- currently set to     256
Block device           252:1

可以看到, logical volume 已经成功的变大为了100GB.

扩大ext4分区

最后一步, 我们需要把logical volume上的ext4分区也扩大, 这样才能真正的存下文件.

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chi-VirtualBox ~ # resize2fs /dev/mint-vg/root 
resize2fs 1.42.5 (29-Jul-2012)
Filesystem at /dev/mint-vg/root is mounted on /; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 7
The filesystem on /dev/mint-vg/root is now 26214400 blocks long.

chi-VirtualBox ~ # df -h
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/mint--vg-root   99G   26G   69G  28% /
none                       4.0K     0  4.0K   0% /sys/fs/cgroup
udev                       985M  4.0K  985M   1% /dev
tmpfs                      201M  896K  200M   1% /run
none                       5.0M     0  5.0M   0% /run/lock
none                      1002M   72K 1002M   1% /run/shm
none                       100M   16K  100M   1% /run/user
/dev/sda1                  228M   75M  141M  35% /boot

可以看到

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下面的空间已经成功扩大了.

关于lvm的一些知识…

相信看了上面的步骤你已经和我一样晕了…下面我来试图解释一下lvm中的各种术语

  • 首先是volume group, 这个你可以想成是扩展分区, 不同的是volume group可以跨多块硬盘多个设备(这是lvm的牛逼之处), 用
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    vgdisplay
    可以查看.
  • 然后是physical volume, 这个就是传统意义上的分区, 例如/dev/sda5, 用
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    可以查看
  • 然后是logical volume, 这个就是lvm中的逻辑分区, 地位相当于逻辑分区. 你硬盘上的目录, 就是挂载在logical volume上的. 用
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    可以查看.

lvm有什么好处?

简单的讲, 就是你可以分出多个物理上的逻辑分区(例如 

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), 然后把它们放到同一个volume group中, 再从volume group中划分出不同的logical volume, 用于不同目录的挂载. 这样, 相当于在物理上的逻辑分区之上又抽象出了新的逻辑分区, 新的逻辑分区可以任意变化大小, 甚至可以横跨不同的硬盘, 非常灵活.

一句话总结一下: 用fdisk创建physical volume, physical volume 组成 volume group, volume group划分为若干logical volume, 目录挂载在logical volume之上.