Linux Operations Practice Test Summary

First, the simple question

1. Five functions of the operating system

A: Job management: Including tasks, interface management, human-computer interaction, graphical interface, voice control and virtual reality, etc.

Document management: Also known as information management;

Storage Management: The essence is the management of the storage space, mainly the main memory management;

Equipment Management: In fact refers to the management of hardware equipment, including the start of input ', allocation, completion and recovery;

Process management: is actually the "time" management of the processor, that is, how to properly allocate the CPU to each task

The five major philosophical ideas of 2.linux

A: All files: The Linux operating system accesses the control computer in the form of access files, such as for various hardware devices. Character devices, sockets, etc. are all mounted by mount

The corresponding device then accesses the corresponding file to achieve the purpose of access, control, etc.

Small, single-purpose use: Programs and executables are not complex, which ensures that the Linux kernel runs efficiently.

Connect programs to accomplish complex tasks: For complex tasks, Linux is done together by combining and connecting multiple simple programs to ensure simple programs

High efficiency, the completion of complex procedures must also be efficient

Avoid confusing graphical interfaces: almost all problems can be solved quickly by using the Linux system's default command interface, unlike window,

Problem due to complex graphical interface response users are difficult to find the problem, can only be restarted or re-install the system to try to solve, this is the Linux operating system

Simple and efficient embodiment.

Configuration data is stored in text: Linux system all services, applications can be modified by any of the editing text tool corresponding configuration text file is very convenient to implement the modification. and

Unlike window, all configuration information is placed in a large and varied binary or 16 registry, which is more complex to modify.

3.RAID Level and introduction

A: RAID-0: The combination of multiple hard disks into a hard disk, to achieve the purpose of parallel read and write data across the hard disk, improve the hard disk read and write speed, the advantage is that the fastest in all RAID read and write speed!

However, the disadvantage is that there is no redundant fault tolerance, once data loss cannot be recovered. (principle: Read-write speed:cpu> memory > HDD >io and Bus device)

RAID-1: A mirrored hard disk is added to each hard drive in the raid, which means that each drive data is backed up, so that even if the primary drive is faulty, the mirrored drive can replace the primary

The hard drive continues to work without being affected, and the benefits are highest in all RAID security! The disadvantage of the corresponding is the lowest utilization! , up to only 50

RAID-5: A storage solution that combines storage performance, data security, and storage costs. It uses disk Striping (hard disk partitioning) technology. RAID 5 requires at least three disks,

Instead of backing up the stored data, RAID 5 stores the data and the corresponding parity information on each disk that makes up the RAID5, and the parity information and the corresponding

The data is stored on separate disks. When one of RAID5 's disk data is damaged, it can recover the corrupted data using the remaining data and the corresponding parity information.

RAID 5 can be understood as a compromise between RAID 0 and RAID 1. RAID 5 can provide data security for the system, but with less protection than mirrors and disk space utilization

Like high. RAID 5 has a similar data read speed as RAID 0, just because a bit more parity information, the speed of writing data is relatively slow to write to a single hard disk,

Using write-back caching can make performance improvements a lot. And because multiple data corresponds to one parity message, RAID 5 has a higher disk space utilization than RAID 1, and storage costs

relatively inexpensive.

RAID-10: It is the first to mirror and then partition the data, and then divide all the drives into two groups, considered as the lowest combination of RAID 0, and then each of the two groups as RAID 1 operation.

RAID-01: In contrast to the RAID 10 program, the partition is then mirrored to two sets of hard disks. It divides all the hard drives into two groups, becoming the lowest combination of RAID 1, while the two groups of hard disks

Each is considered RAID 0 operation when RAID 10 has one hard drive damaged, the remaining drives will continue to operate. Raid 01 Only one hard drive is damaged, and all hard drives in the same group of RAID 0 will stop functioning.

Only other groups of hard drives are operating with less reliability. If you build raid 01 with six hard disks, and then use three RAID 0 for the mirror, then one hard drive will have three hard drives offline. So

RAID 10 is much more common than raid 01, and most retail motherboards support RAID 0/1/5/10 but do not support RAID 01

4. The composition of the computer: hardware: CPU (central processing unit), memory (ROM, RAM), bus (data bus, address bus, control bus), various IO devices.

Software: Operating system, application.

5. Introduce the Linux security model:

Answer: Use user and Group (roles) to control user permissions on files
User login to Linux using account and password
Each file has owner, and owner belongs to a group
Each running process, program has owner and group

6.OSI seven-layer network model Brief introduction

For:

7.TCP three-time handshake, four-time wave waving process

For:

　　

Linux Operations Practice Test Summary