RAID principle and configuration of soft raid

First, RAID: Independent redundant disk array ;

Also known as a redundant array of inexpensive disks (redundant array of inexpensive disk), multiple independent physical disks are combined in different ways to form a virtual disk.

Ii. Why RAID is used in the production environment? What are the advantages of RAID?

1. The advantages of RAID in capacity and management

Easy and flexible capacity expansion

"Virtualization" makes manageability a lot stronger

2. The performance advantage of RAID

Improved performance with disk chunking technology

3. The advantages of RAID in reliability and availability

Reliability through redundancy and hot-standby, heat-exchange lifting forces

Third, the level of RAID

Level: only means the disk organization is different, there is no subordinate points

RAID0: Strip

Working principle:

Distributes data evenly across the array's disks in striped form

The number of disks required:

Greater than or equal to 2 disks

Advantages:

Very high disk read and write efficiency, no verification, not too much CPU resources, design and use of configuration is relatively simple

Disadvantages:

No redundancy and cannot be used in environments with high data security requirements

Applicable field:

Video generation and editing, image editing, other operations that require large transmission bandwidth

RAID1: Mirroring

Working principle:

Multiple copies of data on a virtual disk, on all disks, in a mirrored redundancy

The number of disks required:

2n a minimum of 2

Advantages:

With 100% data redundancy to provide the highest data security, theoretically can achieve twice times the reading speed, design and use is relatively simple.

Disadvantages:

High overhead, only 50% space utilization, no upgrade on write performance, parallel storage, expensive cost

Applicable field:

High-availability, high-security data storage environments such as finance and finance

RAID5:

Working principle:

With an independent access array, the checksum information is distributed evenly across the array's disks.

Number of disks:

Greater than or equal to three

Advantages:

High Read performance

Medium Write performance

Check the distributed access of information to avoid the bottleneck of writing operation

Disadvantages:

Controller design is complex; Disk rebuild process is more responsible

Applicable field:

File server, email server, Web server environment, database application

raid1,0

Combine RAID1 and RAID0; mirror first; striped access

Number of disks required:

2n, n greater than or equal to 2

Advantages:

High reading performance, good writing performance, good data security, allowing n disks to fail at the same time

Disadvantages:

Space utilization is still 50%;

Applicable field:

More for database applications that require high availability and high security

raid0,1

Do a strip first, then mirror it.

Other information is basically similar to radi1,0; the only difference is that write performance is better than read performance

raid5,0

Do the RADI5 first, and then do the strips.

Number of disks required:

Greater than or equal to 6

Advantages:

Better reading performance than RAID5, shorter RAID5 reconstruction time than the same capacity, allowing n disks to fail simultaneously

Disadvantages:

complex design; failure of two disks in the same RAID5 group can cause the entire array to fail

Applicable field:

Applications such as large database servers, application servers, file servers, etc.

There is also a special disk array, JBOD

No performance improvement, no redundancy, 100% space utilization, at least 2 disks; typically used for large databases such as Hadoop

This article from "It Layman teahouse" blog, declined reprint!

RAID principle and configuration of soft raid