调整Linux磁盘分区大小

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参考一：调整Linux磁盘分区大小

在使用linux的过程中, 有时会出现因为安装系统时分区不当导致有的分区空间不足,而有的分区空间过剩的情况.比如: 我在安装系统时给/usr/local分配器了5G的空间,但使用一段过程后发现, /usr/local最多只用到了1G.这样可以将/usr/local大小调整为1G. 空出4G留作他用.本文归纳了在不破快文件系统数据的前提下对文件系统大小进行调整的方法.这里采用的是"拆东墙, 补西墙"的方法. 当然, 如果你的磁盘中有未分区的空闲空间, 你就不用减小某个分区的空间了.

准备工作

(一) 备份

首先组好备份要更改的分区中的文件. 对磁盘的操作也许会导致数据的丢失. 开始工作之前最好将重要的数据保存到别的分区.

(二) 获取相关信息.

1, 运行 $ df , 查看文件系统信息. 记下你想要调整的分区对应的挂载点和设备文件.

这一步是为了查看/usr/local对应/dev/中的哪个设备文件. 本文以/dev/hda7为例.

2, 运行 # sudo fdisk /dev/sda . 进入fdisk , 按下p, 查看磁盘分区信息. 记下/dev/sda8的起始柱面号, 终止柱面号. 设他们分别为start, end. 并记下一个"Unit"包含多少字节.

注意, 文件系统大小和磁盘分区大小是不能等同的: 起码他们的计量单位不同. 在文件系统中, 一般用KB, MB, GB为单位. 但在fdisk中, 是以磁盘的"unit"值(即一个柱面中包含的字节数)来计算的. 我们运行 # fdisk /dev/sda后, fdisk显示如下信息:

Disk /dev/sda: 163.9 GB, 163928604672 bytes
255 heads, 63 sectors/track, 19929 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

(三)计算终止柱面号

e.g: 原先/usr/local的大小为5000 MB, 起始柱面号为2550, 终止柱面号为3157. 那么我现在要将它的大小改为1000MB, 应该这样计算终止柱面号( [3.2] = 4 ):

终止柱面号 = 2550 + [(1000 * 1024 * 1024 ) / 8225280] = 2678

使用fdisk删除原来的分区(以前分区的数据不会丢失!). 然后新建一个分区, 新分区于旧分区唯一的区别就在于分区大小不一样, 这表现在他们终止柱面号不同.

增加分区大小: 终止柱面号设置为空闲空间的最后一个柱面号.减小分区大小: 终止柱面号由计算得出.

开始调整
在开始调整之前, 最好拿一张纸记下要调整的分区的下列信息:

调整前大小, 调整后大小. 它挂载在哪个目录, 对应于/dev/中的哪个设备. 起始, 终止柱面.

e.g: 调整前: 5G, 调整后: 1G, 挂载点: /usr/local, 对应于/dev/hda7. 起始,终止柱面分别为2550, 3157.

1, 卸载分区
最好在runlevel = 1的情况下卸载.
# umount /dev/

2, 检查文件系统的一致性
# fsck -n /dev/

3, 如够是ext3系统, 还要去除日志
# tune2fs -O ^has_journal /dev/

注意: 取出日志后的ext3系统是无法挂载的, 使用
# tune2fs -j /dev/重建日志.

4, 调整文件系统大小
# resize_reiserfs -s 1000M /dev/hda7

调整完文件系统的大小以后，再使用以下命令以文件系统进行全面的检查:
# reiserfsck --check --fix-fixable /dev/hda7

5, 进入fdisk, 调整分区大小.
# fdisk /dev/hda

由于内核仍然使用旧的分区表, 重启之后再进行后面的步骤.

通过以上步骤，我们已经完成了硬盘分区大小调整的操作，接下来回到重新调整文件系统大小的问题上来。由于硬盘分区是按照柱面来计划的，我们要在 resize_reiserfs步骤上就一步到位调整文件系统大小与硬盘分区大小正好相等是比较困难的事情。所以一般是调硬盘分区比文件系统要大一点点，然后再通过以下命令进行同步(当然如果你不在意硬盘分区里面存在部分空间的话也可以忽略以下步骤)：

# umount /home/
# resize_reiserfs /dev/hda6

参考二： esize2fs - ext2 file system resizer

resize2fs 是 ext2 文件系统大小调整工具
可以扩大可以缩小原ext2分区（当然 ext3只是多了 Journal的ext2 也可以）

需要注意的是增大的话
起始柱面不能变

步骤就是：
先fdisk 调整分区
所谓调整也就是删了相关的分区再重建分区
最后在分区上再用 resize2fs 调整文件系统大小

所以一个概念或者说对照就是
文件系统(file system)是在分区(Partition)基础上的

# rpm -qf /sbin/resize2fs
e2fsprogs-1.32-15.1

# rpm -qil e2fsprogs
Name : e2fsprogs Relocations: (not relocatable)
Version : 1.32 Vendor: Red Hat, Inc.
Release : 15.1 Build Date: Mon 04 Oct 2004 10:23:16 PM CST
Install Date: Mon 17 Jan 2005 03:36:34 PM CST Build Host: tweety.build.redhat.com
Group : System Environment/Base Source RPM: e2fsprogs-1.32-15.1.src.rpm
Size : 1069923 License: GPL
Signature : DSA/SHA1, Thu 18 Nov 2004 05:35:43 AM CST, Key ID 219180cddb42a60e
Packager : Red Hat, Inc.
URL : http://e2fsprogs.sourceforge.net/
Summary : Utilities for managing the second extended (ext2) filesystem.
Description :
The e2fsprogs package contains a number of utilities for creating,
checking, modifying, and correcting any inconsistencies in second
extended (ext2) filesystems. E2fsprogs contains e2fsck (used to
repair filesystem inconsistencies after an unclean shutdown), mke2fs
(used to initialize a partition to contain an empty ext2 filesystem),
debugfs (used to examine the internal structure of a filesystem, to
manually repair a corrupted filesystem, or to create test cases for
e2fsck), tune2fs (used to modify filesystem parameters), and most of
the other core ext2fs filesystem utilities.

You should install the e2fsprogs package if you need to manage the
performance of an ext2 filesystem.
/lib/evms/libe2fsim.1.2.1.so
/lib/libcom_err.so.2
/lib/libcom_err.so.2.0
/lib/libe2p.so.2
/lib/libe2p.so.2.3
/lib/libext2fs.so.2
/lib/libext2fs.so.2.4
/lib/libss.so.2
/lib/libss.so.2.0
/lib/libuuid.so.1
/lib/libuuid.so.1.2
/sbin/badblocks
/sbin/debugfs
/sbin/dumpe2fs
/sbin/e2fsck
/sbin/e2image
/sbin/e2label
/sbin/findfs
/sbin/fsck
/sbin/fsck.ext2
/sbin/fsck.ext3
/sbin/mke2fs
/sbin/mkfs.ext2
/sbin/mkfs.ext3
/sbin/resize2fs
/sbin/tune2fs
/usr/bin/chattr
/usr/bin/lsattr
/usr/bin/uuidgen
/usr/sbin/mklost+found
/usr/share/doc/e2fsprogs-1.32
/usr/share/doc/e2fsprogs-1.32/README
/usr/share/doc/e2fsprogs-1.32/RELEASE-NOTES
/usr/share/man/man1/chattr.1.gz
/usr/share/man/man1/lsattr.1.gz
/usr/share/man/man1/uuidgen.1.gz
/usr/share/man/man3/libuuid.3.gz
/usr/share/man/man3/uuid_clear.3.gz
/usr/share/man/man3/uuid_compare.3.gz
/usr/share/man/man3/uuid_copy.3.gz
/usr/share/man/man3/uuid_generate.3.gz
/usr/share/man/man3/uuid_generate_random.3.gz
/usr/share/man/man3/uuid_generate_time.3.gz
/usr/share/man/man3/uuid_is_null.3.gz
/usr/share/man/man3/uuid_parse.3.gz
/usr/share/man/man3/uuid_time.3.gz
/usr/share/man/man3/uuid_unparse.3.gz
/usr/share/man/man8/badblocks.8.gz
/usr/share/man/man8/debugfs.8.gz
/usr/share/man/man8/dumpe2fs.8.gz
/usr/share/man/man8/e2fsck.8.gz
/usr/share/man/man8/e2image.8.gz
/usr/share/man/man8/e2label.8.gz
/usr/share/man/man8/findfs.8.gz
/usr/share/man/man8/fsck.8.gz
/usr/share/man/man8/fsck.ext2.8.gz
/usr/share/man/man8/fsck.ext3.8.gz
/usr/share/man/man8/mke2fs.8.gz
/usr/share/man/man8/mkfs.ext2.8.gz
/usr/share/man/man8/mkfs.ext3.8.gz
/usr/share/man/man8/mklost+found.8.gz
/usr/share/man/man8/resize2fs.8.gz
/usr/share/man/man8/tune2fs.8.gz

# fdisk /dev/sdb
The number of cylinders for this disk is set to 8924.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sdb: 73.4 GB, 73407868928 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 522 4192933+ 82 Linux swap
/dev/sdb2 523 783 2096482+ 83 Linux
/dev/sdb3 784 1436 5245222+ 83 Linux
/dev/sdb4 1437 8924 60147360 f Win95 Ext'd (LBA)
/dev/sdb5 1437 8924 60147328+ 83 Linux

Command (m for help): d
Partition number (1-5): 3

Command (m for help): p

Disk /dev/sdb: 73.4 GB, 73407868928 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 522 4192933+ 82 Linux swap
/dev/sdb2 523 783 2096482+ 83 Linux
/dev/sdb4 1437 8924 60147360 f Win95 Ext'd (LBA)
/dev/sdb5 1437 8924 60147328+ 83 Linux

Command (m for help): d
Partition number (1-5): 2

Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (523-8924, default 523):
Using default value 523
Last cylinder or +size or +sizeM or +sizeK (523-1436, default 1436):
Using default value 1436

Command (m for help): p

Disk /dev/sdb: 73.4 GB, 73407868928 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 522 4192933+ 82 Linux swap
/dev/sdb2 523 1436 7341705 83 Linux
/dev/sdb4 1437 8924 60147360 f Win95 Ext'd (LBA)
/dev/sdb5 1437 8924 60147328+ 83 Linux

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

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

# resize2fs -p /dev/sdb2 7341705
resize2fs 1.32 (09-Nov-2002)
The containing partition (or device) is only 1835426 blocks.
You requested a new size of 7341705 blocks.

Syncing disks.

# resize2fs 1.32 (09-Nov-2002)
The containing partition (or device) is only 1835426 blocks.
You requested a new size of 7341705 blocks.

Syncing disks.

# e2fsck -f /dev/sdb2
e2fsck 1.32 (09-Nov-2002)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/var: 599/262144 files (4.5% non-contiguous), 74698/524120 blocks

# resize2fs -p /dev/sdb2
resize2fs 1.32 (09-Nov-2002)
Begin pass 1 (max = 40)
Extending the inode table XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/sdb2 is now 1835008 blocks long.

然后 mount 上 ls 一下就发现原来 sdb2 的区大了还有 sdb3 的东西也在

RESIZE2FS(8) RESIZE2FS(8)

NAME
resize2fs - ext2 file system resizer

SYNOPSIS
resize2fs [ -d debug-flags ] [ -f ] [ -F ] [ -p ] device [ size ]

DESCRIPTION
The resize2fs program will resize ext2 file systems. It can be used to
enlarge or shrink an ext2 file system located on device so that it will
have size blocks. If the size parameter is not specified, it will
default to the size of the partition. The size parameter may never be
larger than the size of the partition.

The resize2fs program does not manipulate the size of partitions. If
you wish to enlarge a filesystem, you must first make sure you can
expand the size of the underlying partition first. This can be done
using fdisk(8) by deleting the partition and recreating it with a
larger size. When recreating the partition, make sure you create it
with the same starting disk cylinder as before! Otherwise, the resize
operation will certainly not work, and you may lose your entire
filesystem.

If you wish to shrink an ext2 partition, first use resize2fs to shrink
the size of filesystem. Then you may use fdisk(8) to shrink the size
of the partition. When shrinking the size of the partition, make sure
you do not make it smaller than the new size of the ext2 filesystem!

OPTIONS
-d debug-flags
Turns on various resize2fs debugging features, if they have been
compiled into the binary. debug-flags should be computed by
adding the numbers of the desired features from the following
list:
1 - Print out all disk I/O
2 - Debug block relocations
8 - Debug inode relocations
16 - Debug moving the inode table

-p Prints out a percentage completion bars for each resize2fs oper-
ation, so that the user can keep track of what the program is
doing.

-f Forces resize2fs to proceed with the filesystem resize opera-
tion, overriding some safety checks which resize2fs normally
enforces.

-F Flush the filesystem device's buffer caches before beginning.
Only really useful for doing resize2fs time trials.

AUTHOR
resize2fs was written by Theodore Ts'o .

COPYRIGHT
Resize2fs is Copyright 1998 by Theodore Ts'o and PowerQuest, Inc. All
rights reserved. As of April, 2000 Resize2fs may be redistributed
under the terms of the GPL.

SEE ALSO
fdisk(8), e2fsck(8), mke2fs(8)

E2fsprogs version 1.32 November 2002 RESIZE2FS(8)