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服务器安装 centos 的时候，通常 linux 系统分区默认为 3 个分区，主分区最多 4 个，其他可根据自己的需要挂载。
/ 根分区，通常 10-100G 左右（根据总磁盘大小情况）
/boot 系统操作分区（100-500MB 足矣）
/swap 虚拟内存暂存分区（通常是内存的 2 倍）
如果有剩下的磁盘就保留，后期再挂载。安装完系统后就开始格式化剩下的分区，并挂载指派出来。
1、首先查看未指派的分区名称，有的不一样，我的分别是 /dev/sda 和 /dev/sdb，sda 是系统分区，sdb 是存储数据分区。
# fdisk -l
Disk /dev/sda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0x00043041
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 20971519 9436160 8e Linux LVM
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/mapper/cl-root: 8585 MB, 8585740288 bytes, 16769024 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/mapper/cl-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes2、可以看到红色标注的是 10G 的数据磁盘，我们现在执行分区，代码如下：
# fdisk -S 56 /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x52d681d6.
The device presents a logical sector size that is smaller than
the physical sector size. Aligning to a physical sector (or optimal
I/O) size boundary is recommended, or performance may be impacted.
Command (m for help):【输入 n 回车，添加新分区，如果需要更多，请输入 m 回车看帮助】Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):【输入 p 回车，P 的意思是主分区】Partition number (1-4, default 1):【输入数字 1 回车，分区数量】First sector (2048-20971519, default 2048):【默认回车】Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):【默认回车】Using default value 20971519
Partition 1 of type Linux and of size 10 GiB is set
Command (m for help):【输入 wq 保存】The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.3、分区完成。输入 fdisk - l 查看信息
Disk /dev/sda: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0x00043041
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 20971519 9436160 8e Linux LVM
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Disk identifier: 0x52d681d6
Device Boot Start End Blocks Id System
/dev/sdb1 2048 20971519 10484736 83 Linux
Disk /dev/mapper/cl-root: 8585 MB, 8585740288 bytes, 16769024 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk /dev/mapper/cl-swap: 1073 MB, 1073741824 bytes, 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes4、可以查看 /dev/sdb1 已经被默认分区，现在开始格式化此分区。
注意：以下有几种常用磁盘格式，如果你想格式化 ext3 格式, 代码如下;
# mkfs.ext3 /dev/sdb1
格式化 ext4 格式，代码如下；# mkfs.ext4 /dev/sdb1
我这里采用的是 xfs 磁盘格式；代码如下；# mkfs.xfs -f /dev/sdb1
meta-data=/dev/sdb1 isize=512 agcount=4, agsize=655296 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=2621184, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=05、已经格式化成功。将磁盘挂载信息写入到系统配置文件中，不然开机不会自动挂载，代码如下；
# echo‘/dev/sdb1 /www xfs defaults 0 0’>> /etc/fstab
# mkdir /www // 新建挂载目录
# mount -a // 挂载磁盘
# df -h // 查看挂载是否成功
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/cl-root 8.0G 3.1G 5.0G 39% /
devtmpfs 906M 0 906M 0% /dev
tmpfs 916M 0 916M 0% /dev/shm
tmpfs 916M 8.3M 908M 1% /run
tmpfs 916M 0 916M 0% /sys/fs/cgroup
/dev/sda1 1014M 138M 877M 14% /boot
tmpfs 184M 0 184M 0% /run/user/0
/dev/sdb1 10G 33M 10G 1% /www6、可以看到 www 目录已经挂载成功。
扩展阅读，fdisk -S 56 /dev/sdb 的时候输入 m 有帮助信息，下面就列举说明：
a、toggle a bootable flag // 切换一个可启动的标志
b、edit bsd disklabel // 编辑 bsd disklabel
c、toggle the dos compatibility flag // 切换 dos 兼容性模式
d、delete a partition // 删除一个分区
g、create a new empty GPT partition table // 创建一个新的空 GPT 分区表
G、create an IRIX (SGI) partition table // 创建一个 IRIX（SGI）分区表
l、list known partition types // 列出已知的分区类型
m、print this menu // 打印此菜单
n、add a new partition // 添加一个新的分区
o、create a new empty DOS partition table // 创建一个新的空 DOS 分区表
p、print the partition table // 打印分区表
q、quit without saving changes // 退出而不保存更改
s、create a new empty Sun disklabel // 创建一个新的空的 Sun 磁盘标签
t、change a partition’s system id // 更改分区的系统 ID
u、change display/entry units // 更改显示 / 输入单位
v、verify the partition table // 验证分区表
w、write table to disk and exit // 将表写入磁盘保存并退出
x、extra functionality (experts only) // 高级功能（仅限专家）
正文完
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