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 bytes
2、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 bytes
4、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=0
5、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% /www
6、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）
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