centos系统下如何挂载磁盘？
有遇到用户购买我司云服务器后，在安装宝塔面板之前，不会挂载磁盘或没有操作挂载磁盘，从而将数据全部默认安装到了系统盘，进而导致数据盘容量浪费，在此，我司技术部呼吁千万不要将宝塔面板和数据库全部安装到系统盘，一旦重装系统则数据全部会被删除，强烈建议务必要挂载数据磁盘，将所有数据放到数据盘中。
以挂载我司云服务器数据盘/dev/xvdb为例，现针对centos系统挂载数据磁盘方法整理如下：
1、创建挂载目录（以创建www磁盘目录为例）
命令：mkdir -p /www
2、确认是否没有分区的磁盘
命令：fdisk -l
如下：可以看到我司云服务器centos系统数据盘/dev/xvdb，大小41.9GB，数据盘下分区为空白，说明该磁盘未挂载分区;系统盘/dev/xvda，大小10.7GB，系统盘下有两个分区/dev/xvda1 和/dev/xvda2。
[root@XS22218659208 ~]# fdisk -l
Disk /dev/xvdb: 41.9 GB, 41875931136 bytes, 81788928 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 /dev/xvda: 10.7 GB, 10737418240 bytes, 20971520 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 label type: dos
Disk identifier: 0x000d0b25
Device Boot Start End Blocks Id System
/dev/xvda1 * 2048 2099199 1048576 83 Linux
/dev/xvda2 2099200 20971519 9436160 8e Linux LVM
Disk /dev/mapper/centos-root: 8585 MB, 8585740288 bytes, 16769024 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 /dev/mapper/centos-swap: 1073 MB, 1073741824 bytes, 2097152 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
3、为磁盘分区
命令：fdisk /dev/xvdb
如下：
[root@XS22218659208 ~]# fdisk /dev/xvdb
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 0x5d7fdc5a.
CommＡnd (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Ｓelect (default p): p
Partition number (1-4, default 1): 1
First sector (2048-81788927, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-81788927, default 81788927):
Using default value 81788927
Partition 1 of type Linux Ａnd of size 39 GiB is set
CommＡnd (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@XS22218659208 ~]#
4、检查是否分区成功。（分区中带有/dev/xvdb1则代表成功）
命令：fdisk -l
5、格式化分区
命令：mkfs.ext4 /dev/xvdb1
6、将分区挂载信息添加到配置文件/etc/fstab中，实现开机/重启自动挂载
命令：echo "/dev/xvdb1 /www ext4 defaults 0 0" >> /etc/fstab
7、重新挂载所有分区
命令：mount -a
8、检查是否挂载成功
命令：df -h
如下：显示/dev/xvdb1 挂载成功，大小为39G，挂载目录为/www
[root@XS22218659208 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 4.0G 0 4.0G 0% /dev
tmpfs 4.0G 0 4.0G 0% /dev/shm
tmpfs 4.0G 8.4M 4.0G 1% /run
tmpfs 4.0G 0 4.0G 0% /sys/fs/cgroup
/dev/mapper/centos-root 7.8G 1.6G 5.8G 22% /
/dev/xvda1 976M 131M 778M 15% /boot
tmpfs 802M 0 802M 0% /run/user/0
/dev/xvdb1 39G 49M 37G 1% /www
至此，成功挂载磁盘完成。
