In the software model, the operating system is responsible for implementing ...

xanoc76784

For the first time, the term Redundant Array of Independent Disks ( RAID ) was proposed by researchers at the University of California in 1987. RAID technology is used to increase capacity, efficiency and security. There are two types of RAID, software and hardware, which usually has a higher performance than software, but users who cannot use hardware RAID due to lack of budget can use software. In the software model, the operating system is responsible for implementing RAID, and in the hardware model, a part named RAID Controller is responsible for this. RAID techniques: 1-Striping: In this technique, information is divided into parts of a certain size and then this information is written on hard disks, which will increase the storage space. 2- parity: In this technique, a parity code is written on several hard disks at the same time as the information is copied, which increases the security of the information and prevents the deletion of the information.

3-mirroring: In this technique, a copy of the information is stored in the disks, and if one of the disks has a phone numbers list problem, the information is read from the other disk. Commonly used RAID levels: RAID0: In this type of RAID, striping technique is used. Information is divided into equal parts and stored on hard disks. Suppose your information contains four characters A, B, C and D. In this method, A and B are stored in one hard drive and C and D are stored in the second hard drive (assuming there are two hard drives). Now, if the first hard drive has a problem, considering that the information of the two hard drives are dependent on each other, the information on the second hard drive will be useless and practically all the information will be lost. One of the advantages of this type of RAID is to increase the speed of reading and writing, but its main problem is the loss of information in case of a problem with one of the hard drives. If information is important to you, it is not recommended to use this type of RAID. picture(1) RAID1: In this type of RAID, the mirroring technique is used and it is necessary to have at least two hard disks.





Suppose you have two hard drives of 2 TB, which makes a total of 4 TB. By applying the settings based on RAID1, one of the hard drives becomes a mirror of the other hard drive, which means that all the information that is stored in the first hard drive will be stored exactly in the second hard drive. With these conditions, only 2 terabytes can be used out of 4 terabytes. One of the advantages of RAID1 is high data security, in fact, when a problem occurs with the first hard drive, the second hard drive is replaced. Among the disadvantages of this type of RAID, we can mention the increase in cost and the decrease in the speed of writing information on the hard drive. picture (2) RAID5: In this type of RAID, mirroring and parity techniques are used, and having at least three hard disks is required. Like RAID1, information is stored simultaneously in the hard drives and a parity code will be distributed between the hard drives so that if a problem occurs for a hard drive, the information can be recovered using this code.