A few years ago, the name of RAID was very strange vocabulary. Over time, the motherboard included with RAID features gradually increased in the market, and the motherboard that provided RAID functionality is generally possible. Provide RAID 0, 1, 0 1 way, and multi-function card specializing in the RAID function is also easy to find. Now many people want to be a raid to play (really rich), then let's introduce the common RAID model to you.
Lift RAID, including two meanings: A represents Array, which is array; i represents independent, that is to say, there is a hard disk to implement RAID function, overall Different combinations of combination between the RAID card implement different disk performance.
RAID 0
The most basic RAID mode is the RAID 0 mode. The purpose of this mode is to provide the fastest storage speed, not considering security issues, RAID 0 mode works as follows:
RAID 0 uses a certain algorithm to divide a file into several small parts according to the user-defined size. After the file is split, each piece of the RAID 0 mode will store a certain number of file fragments. For example, if there is two hard drives in the RAID 0 mode, the user-defined cutting file size is 64K. At this time, if the RAID controller receives an instruction to store a size of 128K, this file will be Split into two 64K sized files, then the two pieces are stored in the hard disk 1 and hard disk 2, respectively, and stored procedures. The same is true in RAID 0 mode, or use the above example, because the file is splitted on each hard disk, only needs to read 64K size from each of the two hard disks. The file broiler can complete the read, so the time required to read the 128K size file in this RAID 0 mode is the same as the time required to read the 64K size on the normal hard disk. In this RAID 0 mode, it is not only one hard disk because it is stored, but it greatly reduces the time required to store and read data. In theory, RAID 0 can implement write and read files. The speed is doubled.
In addition, there is a situation that when the file size to be stored is smaller than the user-defined divided file size, this file will not be separated, and of course, it will not be stored in the RAID 0 mode. Above the hard disk, at this time, the time required to store (or reading) this file is not reduced by the time required to store and read this file using a single hard disk.
Similarly, if the user sets a small size setting of the divided file, it will make RAID 0 work efficiency is very low. For a very simple example, if the user defines this division size is 1K, in storage (or When reading) a file with a size of 128K, then each hard disk needs to be written 64 times and the file size written per time is 1K, which causes a certain bottleneck effect. If someone will split the file size set, it is better to store data with a hard disk.
As mentioned earlier, RAID 0 can provide a fast storage and read speed, and is not in security, in fact, if a hard disk in RAID 0 is corrupted, the overall data is damaged, and there is no way Data recovery. This makes the safe performance of RAID 0 very poor, so many users do not use the RAID 0 mode for safety performance. Even so, RAID 0 is a combination of speed in all RAID methods, if there is two hard drives in the RAID 0 mode, then the speed of RAID 0's storage reads the data of a single hard disk, if With a 6-fast hard disk, then theoretical rate is 6 times more of a single hard drive. If you use different hard drives in RAID 0 mode, you will cause two aspects. First, the effective hard disk capacity of RAID 0 will be the smallest hard disk capacity to multiply the number of hard drives, because if the smallest hard disk of the capacity is full After that, RAID 0 will still assign file average to various hard drives. At this time, it cannot complete the storage task; secondly, if the hard disk speed in RAID 0 is different, the overall speed will be the speed of the slower hard disk. The number of hard drives, because the RAID 0 mode is required to perform the next storage task to perform the next process, so that other fast hard drives will stop waiting for a slow hard disk to complete storage or read Take the task so that overall performance has decreased. Therefore, it is recommended to use the RAID 0 mode to choose a hard disk having the same capacity and speed, preferably the same brand of the same brand.
RAID 0 faces users who need to quickly store and read speeds, are not considered for system security.
RAID 1
Although speed is important for certain users, some users will consider security performance, RAID 1 is a RAID approach considering security. The working principle of RAID 1 mode is as follows:
When RAID 1 works, each data is sent to each hard disk in the array. When the controller receives a file stored in 64K size, it will send the file to each hard disk in this array. Among them, each hard disk stores this 64K size file. When reading files from the array, the controller performs a read operation from a hard drive in the array.
RAID 1 features a hard disk damage in the array, the data will not be lost. At this time, the controller reads data from another unfailed hard disk, and adds a new hard disk when the array is added. When the error is fixed, the controller uses a mirror to restore the data on the hard disk to the newly added hard disk, so that RAID 1 can be formed from new.
In the RAID 1 mode, the hard disk used is preferably the same, otherwise the case where the hard disk space will be wasted. Since the RAID 1 mode is written in different hard drives, the effective hard disk capacity of the RAID 1 mode is the capacity of the hard disk that is the smallest capacity of the array. For example, if there is a hard disk having a capacity of 20G and a hard disk having a capacity of 20G and a hard disk having a capacity of 20G, then the effective capacity of the overall RAID 1 is 20G, and the 10G capacity left on the 30G hard disk will be wasted. . At the same time, if the speed of the two hard drives is different, the hard disk that is fast faster will still stop waiting for the low-end hard disk to complete the task.
RAID 1 mode is more suitable for users who consider how much speed performance, although the RAID 1 mode is not a combination of speed in all RAID mode, but in the speed of RAID 1 mode in the test, it is indeed It will be slower than a single hard drive. The advantage of RAID 1 is that it will not cause data loss after a hard disk is corrupted.
