Disk Array (RAID)

Disk Array:

Disk Array (Redundant Arrays of Inexpensive Disks, raid) fault-tolerant Inexpensive Disk Array

Disk Arrays include hardware disk arrays and software disk arrays.

Disk arrays are classified into the following levels:

Raid-0 (equivalent mode): optimal performance

In this mode, disks of the same model and capacity are used for the best effect.

In this mode, raid switches the disk out of an equal number of blocks (for example, 4 kb). When an archive is written to raid, the archive is stored on each disk in sequence, because each disk is staggered, the data size stored on each disk is equal. The total raid capacity is the sum of the disk capacity.

However, a disk of this level may cause data damage. Data loss may occur if any of the hard disks fails.

When the disk capacity is different, the raid performance is also affected. For example, when a 200 m disk and a 500 m disk are saved to 200 m, the data sizes of the two hard disks are the same, both of which are m, but the data is stored in the hard disks, it will be written into a hard disk of MB, which will greatly affect the raid performance.

Raid-1 (image mode): Full backup

In this mode, when data is stored, the data is copied in multiple copies and stored in different hard disks.

The data ship will be copied multiple copies from the dual bus to each disk, and the data volume increases. Therefore, when a large number of RAID-1 writes, the write efficiency may become very poor, if you use hardware raid, the disk array will be automatically copied instead of using the system bus, which may be better.

Raid-1 because the data on the two hard disks is the same, the biggest data is data backup. However, because half of the hard disks are being backed up, the disk utilization is not high, the Write Performance of RAID-1 is poor, but the read performance is acceptable. This is because two copies of data are on different disks. If multiple progresses read the same group of data, raid-1 is automatically balanced in the middle.

This mode also requires the same disk capacity. For raid-1 composed of different capacities, the total capacity is dominated by the smallest disk capacity.

RAID 0 + 1 or raid 1 + 0

RAID 0 + 1 is: First let two hard disks constitute raid-0, and there are two groups, then the two groups of RAID-0 constitute raid-1, the formation of RAID 0 + 1

The same applies to raid1 + 0.

The combination of RAID 0 + 1 or raid 1 + 0 also inherits the advantages and disadvantages of RAID-0 and raid-1.

 

 

 

 

Reference: laruence's Linux Private food Basics

Disk Array (RAID)