RAID disk array on Linux system build-up

RAID-independent Redundant disk array

Disk array (redundant Arrays of independent Disks,raid), with the meaning of "redundant array of independent disks".
The disk array is made up of many inexpensive disks, combined into a large disk group, which uses individual disks to provide data with the added effect to improve the performance of the entire disk system. Using this technique, the data is cut into many sections, which are stored on each hard drive.
The disk array can also take advantage of the same-bit checking (Parity check) concept, in the array of any one hard disk failure, can still read the data, when the data is reconstructed, the data is computed and re-placed into the new hard disk.
This time we mainly discuss the concepts and configuration of common RAID0, RAID1, RAID5, Raid6
First we use the VMware Workstation Pro virtual machine for trial discussion

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RAID 0

RAID 0 is the first RAID mode, data stripping. RAID 0 is the simplest form of a disk array, requiring more than 2 hard drives and low cost to improve performance and throughput across the entire disk. RAID 0 does not provide redundancy or bug fixes, but the implementation cost is minimal.

RAID 1
RAID 1
RAID 1 is called a disk image, the principle is to mirror the data of one disk to another disk, that is, the data will be written to a disk, the same time on another piece of idle disk to generate image files, without affecting the performance of the maximum guarantee system reliability and repair, As long as there is at least one disk in any pair of mirrors in the system can be used, and even in half the number of hard disk problems when the system can operate normally, when a hard disk fails, the system will ignore the hard disk, instead of using the remaining mirror disk to read and write data, with good disk redundancy capability.

RAID5: Isolated disk structure for distributed parity

As you can see from it, its parity code exists on all disks. RAID5 's readout efficiency is very high, writing efficiency is general, block-type collective access efficiency is good. Because parity codes are on different disks, reliability is improved. But it does not solve the parallelism of data transmission, and the design of controller is very difficult. For RAID 5, most data transfers operate on only one disk, which can be done in parallel. In RAID 5 There is a "write loss", that is, each write operation, will produce four actual read/write operations, two reads old data and parity information, two times write new data and parity information.

RAID6: Stand-alone disk structure with parity codes for two distributed stores

RAID6 technology is a raid method designed to further enhance data protection based on RAID 5, which is actually an extended RAID 5 rating. Unlike RAID 5, where there is a peer data XOR check area on each hard disk, there is also an XOR check area for each block of data. Of course, the current disk data block checksum data can not exist on the current disk but interleaved storage. In this way, the data redundancy performance of RAID 6 is quite good because there are two checksum protection barriers per data block (one layered check and one is the overall check). However, due to the addition of a checksum, the efficiency of writing is worse than RAID 5, and the design of the control system is more complex, and the second block also reduces the effective storage space.

So the whole experiment was successful.
If there are any mistakes in this, please correct them.
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RAID disk array on Linux system build-up