一、給主機添加一塊新硬盤sdb（也可用原有的sda進行操作）
二、步驟
1.查看現有分區
[19:34:36 root@centos7 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 100G 0 part /
├─sda3 8:3 0 50G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 3G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
sdc 8:32 0 20G 0 disk
sr0 11:0 1 10G 0 rom /run/media/root/CentOS 7 x86_642.查看fdisk命令幫助
[08:48:17 root@centos7 ~]#fdisk /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.
Command (m for help): m //輸入m查看幫助
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition //刪除分區
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types
m print this menu
n add a new partition //創建新分區
o create a new empty DOS partition table
p print the partition table //查看分區表
q quit without saving changes // 不保存退出
s create a new empty Sun disklabel
t change a partitions system id //更改分區系統id
u change display/entry units
v verify the partition table
w write table to disk and exit //保存並退出
x extra functionality (experts only)3.開始創建分區
Command (m for help): n //創建新分區
Partition type: //分區類型
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): //默認主分區
Using default response p
Partition number (1-4, default 1): //分區編號，默認1
First sector (2048-41943039, default 2048): //起始字節數
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +1G
//創建1G大小的新分區
Partition 1 of type Linux and of size 1 GiB is set
Command (m for help): P //查看創建的分區
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0xfd655652
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
//分區已建好Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p):
Using default response p
Partition number (2-4, default 2):
First sector (2099200-41943039, default 2099200): 2300000
//此處跳過起始字節號
Last sector, +sectors or +size{K,M,G} (2300000-41943039, default 41943039): 2500000 //終止字節號
Partition 2 of type Linux and of size 97.7 MiB is set
Command (m for help): n //繼續創建新分區
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p):
Using default response p
Partition number (3,4, default 3):
First sector ('2099200'-41943039, default 2099200): //此處起始字節已有變化
Using default value 2099200
Last sector, +sectors or +size{K,M,G} (2099200-2299999, default 2299999):
+2G //此處要創建的分區大小已被限制，掉進前面跨過的"夾縫"
Value out of range. //顯示超出範圍，但磁盤空間還剩很多
Last sector, +sectors or +size{K,M,G} (2099200-2299999, default 2299999):
Using default value 2299999
Partition 3 of type Linux and of size 98 MiB is set
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0xfd655652
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
/dev/sdb2 2300000 2500000 100000+ 83 Linux
/dev/sdb3 2099200 2299999 100400 83 Linux
Partition table entries are not in disk order //分區表條目不按磁盤順序排列（若要避免這種情況發生，創建分區時儘量使字節號連續，中間不要有跨越）
4.保存退出，查看分區已建立好
Command (m for help): w //保存並退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[08:53:53 root@centos7 ~]#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 100G 0 part /
├─sda3 8:3 0 50G 0 part /data
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 3G 0 part [SWAP]
sdb 8:16 0 20G 0 disk
├─sdb1 8:17 0 1G 0 part
├─sdb2 8:18 0 97.7M 0 part //分區已創建成功
└─sdb3 8:19 0 98M 0 part
sdc 8:32 0 20G 0 disk
sr0 11:0 1 10G 0 rom /run/media/root/CentOS 7 x86_64