Server RAID 0 + 1 (10) Hard Disk Array Construction Diagram

So how can we solve the bottleneck of hard disk access speed? Creating a raid array with multiple hard disks is a better solution. However, due to the lack of practical experience, many network administrators only have vague concepts about RAID technology, we will share with you the basic raid knowledge and the most common RAID 0 + 1 instance creation.
Raid is a Redundant Array of low-cost disks. It uses multiple physical hard disks to form a logical hard disk with functions such as acceleration, automatic backup, and data damage recovery.
To meet the needs of different working environments, RAID technology is divided into eight types for RAID 0-7. Each array has its own advantages and disadvantages. For example, the raid 1 array emphasizes the security of disk data, the RAID 0 array improves access speed, and the RAID 5 array ensures both speed and security. Next, let's take a look at the specific characteristics of commonly used arrays.
Common raid array types
RAID 0
A raid 0 array is a data stripping array. Its primary feature is that the accessed data is split into strips and stored on each physical disk. The advantage of this processing is that it can be accessed in parallel to achieve double or multiple times of access speed. The simplest RAID 0 array provides double transmission speed with two hard disks. If the array card can support multiple hard disks to form RAID 0, then we can get n times the transmission speed (n is the number of hard disks attached to the array.
The disadvantage of this array is that data security is weak. As long as a hard disk in the array fails, all data will be lost. Therefore, in order to strike a better balance between data vulnerability and speed, RAID 0 usually only uses two hard disks in actual use, achieving double transmission speed and reducing stability by half, it is used to store VOD files, temporary files, and other data with low security requirements.
Raid 1
Raid 1 array (Data mirror) is a data mirror array, which provides excellent data security. The entire array requires at least two hard disks. When writing data, the data is backed up to another hard disk. Therefore, even if one hard disk fails and data is damaged, the file will not be lost. However, the cost is that half of the hard disks in the array are used for instant image backup. The capacity is half of the total capacity of the hard disks in the array, and the speed is not improved.
RAID 0 + 1
In order to combine the fast access feature of RAID 0 with the advantages of RAID 1 data security, RAID 0 + 1 arrays were designed. This array requires at least four hard disks to be created. Two hard disks are used to access data, and the two are used to mirror data. The two hard disks used to store data are divided into parallel access bars to achieve double data access speeds, while the other two hard disks instantly create images for disks with parallel access bars, to ensure that any disk is faulty and data will not be lost.
This array is widely used in Internet cafes and small-sized enterprises because it ensures access speed and data security.
RAID 3 and RAID 5
RAID 3 and RAID 5 both adopt the data storage method of verification. The difference is that raid 3 uses a physical hard disk to store the verification data, while the hard disk that stores data has several hard disks working in parallel at the same time. Whether the data on each hard disk is modified, the verified data hard disk will be modified at the same time, this results in a heavy workload on the verification hard disk, affecting data storage efficiency, while RAID 5 is the opposite, it divides the verification data into blocks and stores them on each hard disk to solve the bottleneck of data storage.
The RAID 5 array card is expensive, so this array is currently only used in large enterprises, and rarely used by Internet cafes.
RAID 0 + 1 practice
After learning about various RAID arrays, let's take the RAID 0 + 1 settings commonly used in Internet cafes as an example. The whole setting process is illustrated.
First, prepare four hard disks, a computer with a blank PCI card or a PCI-E slot (depending on the interface of the RAID card), a RAID card (if the motherboard has integrated the RAID card, then do not need ).
Figure 1
　　
Install the RAID card to the motherboard and connect the four hard disks to the data interface of the RAID card. Turn on the computer and follow the instructions to enter the raid settings screen. In this example, the trak100 array card is used and the "tab" button is used as the setting hot key. Therefore, press the "tab" key to go to the raid setting screen.
After entering the raid setting environment, press 3 and select the "define array" option to enter the raid definition window.
Figure 2
　　
Press enter in the raid definition window to enter the raid editing window. You can set raid mode in the editing window. Note that, many raid cards use the storage mode, where the "stripe" bar storage mode is RAID 0; "mirror" indicates RAID 1; "Mirror/stripe" indicates the raid0 + 1 mode. You can use the space key to switch the raid mode. Here, select "mirror/stripe" mode and set the four hard disks in the channel to "Y. After setting, press Ctrl + Y to save the setting result.
Figure 3
　　
Note that the RAID 0 + 1 mode cannot be set for less than four hard disks, and the "mirror/stripe" mode is not displayed.
After setting, you can see that the entire disk capacity has reached 80 GB, which is based on the features of RAID 0 + 1. Its capacity is twice the minimum hard disk base. Because the minimum hard disk used by the author is 40 GB, after the configuration is complete, the capacity is 40 Gb * 2, if four 80 GB hard disks are used, set the "mirror/stripe" mode to 2*80 GB.
Figure 4
　　
Press the "ESC" button to exit the settings window. In the displayed dialog box, enter "Y" to confirm the settings and restart the system.
Figure 5
　　
After the system is restarted, the raid settings are displayed, including the working mode, total array capacity, and status. Now, you can partition, install the system, software, and perform other operations on the array. For the operating system, the entire array is equivalent to a hard disk.
　　
If a hard disk fails, you only need to find the damaged hard disk, select 2 in the raid definition window, and rebuild the raid to reconstruct the array.