Analysis of the "Those Things" of Data Storage (Wen not send book)
Write in front
For operation and maintenance, data access, security, and storage are also crucial points. There are also quite a few technical points for data storage, covering a wide range. Today, migrant workers come to talk to all the friends about data Stored "those things"
Introduction to storage concept
Data storage objects include temporary files generated by the data stream during processing or information that needs to be searched during processing. The data is recorded on the internal or external storage medium of the computer in a certain format. Data storage should be named, and this naming should reflect the compositional meaning of information characteristics. Data flow reflects the data flowing in the system and shows the characteristics of dynamic data; data storage reflects the static data in the system and shows the characteristics of static data. The explanation comes from Baidu Encyclopedia. 
The migrant worker sums it up in one sentence: Data storage is to store a certain amount of data into different storage media through different storage architectures.
Storage media introduction
Disks and tapes are commonly used storage media.
Disks are divided into mechanical disks, SSDs, and other types of 
data storage organization, which differs depending on the storage medium. Data on the tape is only accessed in sequential file mode; on the disk, sequential access or direct access can be used as required. The data storage method is closely related to the data file organization. The key is to establish the corresponding relationship between the logical and physical sequence of the records and determine the storage address to improve the data access speed.
Storage method
DAS directly attached storage method
Just like ordinary PC storage, the storage method of adding external storage devices directly inside the server to store data
is more suitable for small network structures with small data volume and low requirements for data transmission and reading speed.
NAS network storage mode in the scenario
It uses a file service that is independent of the application server and is developed for network data storage to connect all storage devices. In this way, data is stored.
This storage method can be used to install and deploy for all application services. It is relatively simple, plug and play, and does not depend on the operating system. The disadvantage is that the storage performance is not very good.
SAN storage mode
This storage method was introduced by IBM in 1991. It is a storage method based on optical fiber media. Its composition is as follows:
1) Storage and backup equipment: including tapes, disks and optical disc libraries.
2) Fibre Channel network connection components: including host bus adapter cards, drivers, optical cables, hubs, switches, bridges between Fibre Channel and SCSI
3) Application and management software: including backup software, storage resource management software and storage devices Management software.
Introduction to Disk Array System
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Due to the increase in data storage capacity, a single disk device can no longer meet the normal storage requirements, so the concept of disk array system is introduced. Commonly used disk arrays include the following
RAID 0 RAID 0
is the best read and write performance of all disk arrays , And the simplest way to achieve
But its shortcoming is that there is no data redundancy and recovery mechanism. It needs at least two disks to form, so that the space of the two disks is superimposed to form a new large storage capacity disk. Due to its shortcomings, when If a disk is damaged, it will cause data loss that cannot be recovered. This kind of array can store a large amount of log data
RAID 1
RAID 1 is called a mirrored array, so the disks in the structure are mirrored and prepared for each other
This structure requires at least two disks. When one disk is damaged, the data can be recovered immediately. Its read performance is better, but the storage performance is poor, because the same data needs to be written to two disks.
RAID 10 01
RAID10 requires four disks to build, theoretically two disks can be used, but there is no practical significance
This type of structure requires the best disk capacity to be consistent, otherwise the entire array can only identify the smallest capacity disk device. It is two groups of RAID1 working independently, and then forming an array structure like RAID0
RAID01 (or call it RAID0+1)
Its structure is to first compose the disks into RAID0, and then form multiple independent RAID1
The RAID5
structure requires at least three disks
It is based on the principle of even parity group, its core XOR algorithm, may allow a damaged disk, then this XOR algorithm, can quickly complete the data recovery
fan second wave benefits
please see below 
send books Rule As follows:
1. Press and hold the mini program to scan the QR code to participate in the lottery and give out a copy (WEB actual combat)
2. Write the story of your love and death with the operation and maintenance work in the text, and select the message to like the first one and give out a copy (core System command)
3. Winners will send their mobile phone number + name + delivery address in the background of the official account within two hours, and they will automatically be deemed to have given up if
the time expires. 4. This event is limited to followers of the official account (the more exciting the message, the more exciting the message Opportunity to be selected)
5. Event deadline at 10:30, February 3, 2018 
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