What is RAID (Redundant Array of Independent Disks)?

Disk arrays (Redundant Arrays of Independent Drives, RAID) have the meaning of "redundant array of independent disks". ^[1]

A redundant array of independent disks (RAID) is a method of storing the same data in different places (and therefore redundantly) on multiple hard disks. By placing data on multiple hard disks, input and output operations can be overlapped in a balanced manner to improve performance. Because multiple hard drives are added

RAID technology has the following three basic functions:

(1) Stripe the data on the disk to achieve block access to the data, reduce the mechanical seek time of the disk, and improve the data access speed. ^[3]

There are three types of disk arrays, one is external

The disk array is a standalone system

1.DAS--direct access storage device

DAS is centered on the server. Traditional network storage devices connect the RAID hard disk array directly to the server of the network system. This form of network storage structure is called DAS (Direct Attached Storage). ^[6]

Strengthening the daily management and maintenance of disk arrays is an important means to ensure the normal and efficient work of disk arrays. As a storage manager, you should pay attention to the following during daily maintenance: ^[7]

At present, there are mainly three types of RAID array technologies for solid-state hard disks, of which hybrid RAID arrays constructed by the combination of solid-state hard disks and mechanical hard disks achieve complementary characteristics of the two. With the continuous improvement of the cost performance of solid-state hard disks, the development of RAID arrays formed by the combination of solid-state hard disks and solid-state hard disks and the pure solid-state hard disk RAID arrays formed by the combination of flash memory chips and chips of solid-state hard disks has been advanced. Because the current price of solid state hard disks is higher than that of mechanical hard disks, compared with other pure solid state hard disk RAID arrays, hybrid RAID arrays composed of solid state hard disks and mechanical hard disks have greater advantages in terms of cost control. However, in terms of performance and reliability, a RAID array composed of multiple solid-state hard disks is better than a hybrid RAID array composed of solid-state hard disks and mechanical hard disks. At present, most solid-state hard disk manufacturers use chip-level RAID arrays inside solid-state hard disks to further Improve performance and reduce power consumption. ^[8]

For iRAID with embedded RAID array technology, the preliminary research results of this structure show that the RAID system will no longer be a group of independent drives, and there may be only a single high-density disk in the future. This will make the disk arrays of these storage systems, such as cloud storage systems, have greater improvements in performance, power consumption, and volume, further reduce costs, and make maintenance easier. Therefore, the embedded RAID technology will become one of the main research directions of the solid-state hard disk RAID array technology, which has broad application prospects, involving education, entertainment, national defense and other application areas, especially in aerospace, military and other complex working environments. Areas with high requirements and high levels of data security will make a big difference. In addition, because there is less research on evaluating the reliability of solid-state hard disk RAID, it is necessary to improve the evaluation system and method for RAID reliability as soon as possible. Therefore, reliability analysis and research will also become one of the research focuses of solid-state hard disk RAID array technology. ^[8]

In addition, the following two aspects will also receive attention in the research of solid state disk RAID array technology. ^[8]

1) Research on big data storage structure and search engine. Data storage systems are at the core of determining data mining performance and cost. The new big data storage architecture can integrate every storage drive in distributed and embedded search engines, break through the limitations of data throughput and data access storage systems, and increase the bandwidth of big data storage interfaces. ^[8]

2) Research on rapid reconstruction mechanism. The RAID structure of the solid state hard disk adopts the corresponding reconstruction mechanism, which will speed up the entire reconstruction process from statistical errors to data recovery, and also help reduce the risk of data loss during the reconstruction process. The reconstruction mechanism is indispensable for a complete solid state hard disk RAID structure. It needs to be developed and optimized based on the characteristics of its RAID array. ^[8]