RAID is mature. Disk Redundancy Array Technology Resolution

If you are still calculating the capacity of a multi-channel memory of more than 100 yuan to improve the performance by a few percent, I tell you that you are out of date. Because RAID is mature, and mature. Want to know why? Then ask the students and Kiki to learn the theory of RAID.

Tips:

RAID, English full name Redundant Arrays of Independent Disks, redundant array of disks, said simple, as long as users set up it, then this technology can make multiple hard drives Working together, the speed and security of the hard disk are greatly improved.

RAID is very mature

RAID is mature, mainly from a technical point of view. Although the cost of building RAID before was high, you need to buy a RAID card (Figure 1), but the technology is very mature, mainly because RAID technology has been "served" in the server industry for many years before entering the ordinary desktop market. RAID is just a family name. It is also divided into RAID0, RAID1, RAID0+1, RAID5, JBOD and other modes according to different characteristics. What we are going to talk about today is RAID0 with a biased speed, RAID1 with a biased security, and RAID5 with both security and speed.

RAID0 mode: Long live speed!

It is not difficult to understand RAID0. Students only need to look at Figure 2 and read the following texts. The top frame of Figure 2 is loaded with 6 balls. We can think of them as the 6 data waiting to be written to the hard disk, which are represented by the numbers 1 to 6. After RAID0 is formed, the data is written to the hard disk. When the RAID controller writes, the RAID controller allocates them, and puts data 1, data 3, and data 5 into the hard disk A, and puts the data 2, data 4, and data 6 into Hard disk B, because the hard disk works at the same time, so the speed of reading and writing can be seen as doubled. In terms of capacity, if two hard disks are built with RAID0, the total hard disk capacity will be twice that of the lower capacity hard disk. For example, 160GB and 250GB hard drives, the total capacity is 320GB (160GB × 2). Speed ​​increase, capacity is not reduced. For students who like to play games, watch HD videos, etc., the temptation is too big. The actual test data also proved that the RAID0 speed is obviously improved. For example, when you open a 1.7GB TIFF image with Photoshop, the computer with RAID0 mode is almost twice as fast as the computer with the same single hard disk.

Don't look at RAID0 speed is a lot faster, but its security is not flattering. Still taking Figure 2 as an example, students can see the two hard disks after RAID 0 are built, each storing data that the other party does not have. That is to say, once the hard disk A is broken, the original photo composed of 6 "data balls" will be unable to be retrieved because three of them are missing. At this time, the three balls placed in the hard disk B are completely Useless. So RAID0 is suitable for people who don't store important data on their computers.

Tips: Set up RAID0, at least two hard drives, but too many hard drives to build RAID0, will create security risks, after all, more than one hard drive, the chance of failure is greater.

RAID1 mode: Safety first!

The speed of RAID0 can really improve the performance of the computer's disk, but the security is not high. Fortunately, the RAID family has a member who puts data security first - RAID1. As shown in Figure 3, the same six "data balls" waiting to be written are allocated by the RAID controller. As you can see, the data balls entering the two hard disks are all six, which is the same as before writing. This is equivalent to double insurance for the data. Once the hard disk A is broken, because there is still complete data in the hard disk B, then You can get this data back. However, the data transfer speed of RAID1 is almost the same as that of a single hard disk, but the security is improved. Like RAID0, RAID1 also requires two hard drives to be built. Take two hard drives as an example. The capacity after RAID1 is equal to the capacity of a lower-capacity hard disk, such as 160GB and 250GB. The final capacity is 160GB.

From the characteristics of RAID1, you can also judge the people who are suitable for those who have higher requirements for data security.

RAID5 mode: safe and fast!

After reading the above description about RAID0 and RAID1, many students will definitely feel that the two RAID modes are too extreme. Are there two models that are available? That is RAID5. Unlike RAID 5, the first two modes require at least three hard drives to be built.

With the foundation of the previous two modes, it is not difficult to understand RAID5. As shown in Figure 4, there are still 6 "data balls". When data 1 and data 2 are written to hard disk A and hard disk B, respectively, hard disk C will write a red ball A that plays the role of backup. You can think of red ball. A is a combination of the ball 1 and the ball 2. The data is continuously written in such a manner that the ball 3 is written to the hard disk C, the ball 4 is written to the hard disk A, and a red ball B is backed up in the hard disk B. When hard disk A is broken, data 1 and data 4 are lost. At this time, the red ball A originally containing the data 1 and the red ball B containing the data 4 will help restore the data, thereby ensuring the security of the data.

RAID is ripe

The technology is not mature enough. The most important thing for students is the cost of setting up RAID. You may wish to work with Kiki to calculate the account. To set up RAID0 as an example, a 160GB hard drive costs more than 300 yuan, and two hard drives cost more than 600 yuan. And the extra 300 yuan is enough to double the speed and capacity of your hard drive. And more than 300 yuan is now adding 3GB of DDR2 memory money, to know that several GB memory to form a dual-channel performance improvement in many cases far behind the performance improvement brought by the formation of RAID0. So RAID technology is now mature.