Disk management
df command
df=disk filesystem is a command used to view the total capacity, usage, remaining capacity and other information of the mounted disk. It can be used directly without any parameters. The default unit of capacity is kilobytes (KByte).
[root@test-01 ~]# df
文件系统 1K-块 已用 可用 已用% 挂载点
/dev/sda3 16659456 872980 15786476 6% /
devtmpfs 929836 0 929836 0% /dev
tmpfs 935392 0 935392 0% /dev/shm
tmpfs 935392 8692 926700 1% /run
tmpfs 935392 0 935392 0% /sys/fs/cgroup
/dev/sda1 201388 75920 125468 38% /boot
The following mount points in the above information, like / , /boot , are the partitions we divide when installing the system; /dev , /dev/shm , which are memory partitions, the default size is 1/2 of the memory, If we save the file in this partition, the file will disappear after reboot. Other partitions like /run, /sys/fs/cgroup are temporary partitions, and these partitions do not need to be moved during normal work.
Common parameters of the df command, -i,-h,-k,-m
- df -i: Indicates to check the usage of inodes. If inodes are used 100%, even if there is space in the partition, you cannot write anything in it, and the system will prompt that the disk space is full.
[root@test-01 ~]# df -i
文件系统 Inode 已用(I) 可用(I) 已用(I)% 挂载点
/dev/sda3 16669696 23863 16645833 1% /
devtmpfs 232459 365 232094 1% /dev
tmpfs 233848 1 233847 1% /dev/shm
tmpfs 233848 409 233439 1% /run
tmpfs 233848 13 233835 1% /sys/fs/cgroup
/dev/sda1 204800 330 204470 1% /boot
** A little trick, many of the contents displayed directly by this command are temporary partitions and memory partitions, which affect us to view the disk information we need. You can use df -i | grep -v tmpfs , the meaning behind the pipe character is to filter out Partition content with tmpfs. The display content of df -i | grep -v tmpfs can be clearly seen, the temporary partition and memory partition will not be displayed
[root@test-01 ~]# df -i | grep -v tmpfs
文件系统 Inode 已用(I) 可用(I) 已用(I)% 挂载点
/dev/sda3 16669696 23863 16645833 1% /
/dev/sda1 204800 330 204470 1% /boot
- df -h indicates that the content is displayed in an adaptive appropriate capacity unit
- df -k and df -m respectively indicate that the display operation in KB and MB is as follows:
[root@test-01 ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/sda3 16G 853M 16G 6% /
devtmpfs 909M 0 909M 0% /dev
tmpfs 914M 0 914M 0% /dev/shm
tmpfs 914M 8.5M 906M 1% /run
tmpfs 914M 0 914M 0% /sys/fs/cgroup
/dev/sda1 197M 75M 123M 38% /boot
[root@test-01 ~]# df -k
文件系统 1K-块 已用 可用 已用% 挂载点
/dev/sda3 16659456 873004 15786452 6% /
devtmpfs 929836 0 929836 0% /dev
tmpfs 935392 0 935392 0% /dev/shm
tmpfs 935392 8664 926728 1% /run
tmpfs 935392 0 935392 0% /sys/fs/cgroup
/dev/sda1 201388 75920 125468 38% /boot
[root@test-01 ~]# df -m
文件系统 1M-块 已用 可用 已用% 挂载点
/dev/sda3 16269 853 15417 6% /
devtmpfs 909 0 909 0% /dev
tmpfs 914 0 914 0% /dev/shm
tmpfs 914 9 906 1% /run
tmpfs 914 0 914 0% /sys/fs/cgroup
/dev/sda1 197 75 123 38% /boot
du command
du =disk useage is used to view the size of the space occupied by a file or directory, the format is du_ [parameter] filename _ The commonly used parameters of this command are: -a , -b , -k , -m , -s , -c , -h
- -a : Indicates that the size of the space occupied by all files and directories is listed. If the du command does not add any parameters, it will only list the size of the directory (including subdirectories). If du does not specify a unit, the default display unit is KB.
[root@test-01 ~]# du -a /root
4 /root/.bash_logout
4 /root/.bash_profile
4 /root/.bashrc
4 /root/.cshrc
4 /root/.tcshrc
4 /root/anaconda-ks.cfg
12 /root/.bash_history
12 /root/.ssh/.authorized_keys.swp
4 /root/.ssh/authorized_keys
16 /root/.ssh
0 /root/4
0 /root/pawd
56 /root
[root@test-01 ~]# du /root
16 /root/.ssh
0 /root/4
56 /root
du - b ,-k .-m indicates that the space unit is displayed in Byte, KB, MB. The du -c command, which means the final sum, is not commonly used. The du -s command, which only lists the sum, is commonly used.
disk partition
- Adding disks, most servers now support hot-swappable disks. In the power-on state, directly insert new disks, and the system can also recognize them. To use a virtual machine in an experimental environment, you need to restart the virtual machine after adding disks.
- Use the fdisk command to view the list of disk devices and partitions in the system. fdisk -l , without the device name, will display a list of all disk devices and partitions. fdisk -l plus the device name will list the partition table of the device. The following is the result obtained by running fdisk -l after restarting the virtual machine after adding the hard disk:
[root@test-01 ~]# fdisk -l
磁盘 /dev/sda：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
磁盘标签类型：dos
磁盘标识符：0x0009b48b
设备 Boot Start End Blocks Id System
/dev/sda1 * 2048 411647 204800 83 Linux
/dev/sda2 411648 8603647 4096000 82 Linux swap / Solaris
/dev/sda3 8603648 41943039 16669696 83 Linux
磁盘 /dev/sdb：21.5 GB, 21474836480 字节，41943040 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：512 字节 / 512 字节
As we can see above, the newly added hard disk has been recognized by the system, and the name is: /dev/sdb. Next we still use the fdisk command to partition the hard disk.
Common parameters of the fdisk command,
- -p : Indicates to print the partition status of the current disk.
- -n: Create a new partition.
- -w: save and exit
- -q: means do not save the settings and exit directly
- -d: Indicates to delete a partition. Let's demonstrate creating a new partition on the new disk:
命令(输入 m 获取帮助)：n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
分区号 (1-4，默认 1)：
起始 扇区 (2048-41943039，默认为 2048)：
将使用默认值 2048
Last 扇区, +扇区 or +size{K,M,G} (2048-41943039，默认为 41943039)：+8G
分区 1 已设置为 Linux 类型，大小设为 8 GiB
This is the way to create a new partition.