Software RAID has three disadvantages: ① it takes up memory space; ② occupy CPU resources; Software RAID programs cannot make the disk partition on which the operating system is installed into RAID mode. Because the RAID program runs on top of the operating system, the RAID functionality cannot be implemented until the operating system is booted. In other words, if the operating system is corrupted, the RAID program will not run, and the data on the disk will become a bunch of useless stuff. Because the data on the RAID disk can only be recognized and read and write correctly by the program that implements the corresponding RAID algorithm. If there is no corresponding RAID program, the data on the physical disk is just a few fragments, and only the RAID program can combine these fragments. Fortunately, most of the current RAID program will store their own algorithm information on the disk, once the operating system has a problem, or the host hardware has a problem, you can connect these disks to other machines, and then install the same RAID software. After the RAID software has read the RAID information stored in a fixed area on the hard disk, it can continue to use it. Software RAID has so many shortcomings that people are constantly thinking about more methods to implement RAID. Since software has so many drawbacks, what about hardware? RAID card is a method to implement RAID function with independent hardware. To realize RAID function in hardware, we must find a physical hardware as a carrier, SCSI card or motherboard on the south bridge is undoubtedly the carrier. Extra chips have been added to SCSI cards to implement RAID functions. These chips are specially used to execute RAID algorithm, can be ASIC such as high cost and high speed computing chip, can also be general instruction CPU such as general code execution chip, code can be loaded from ROM directly to execute, can also be loaded into RAM before execution, so as to realize RAID function. A RAID card (SCSI card or IDE expansion card) is called a RAID card. Similarly, the RAID function can also be implemented on the south bridge chip of the motherboard. Because the chips in the south bridge cannot rely on the CPU to perform their functions, these chips rely entirely on the circuit logic to operate on their own, and although they are fast, they are less powerful than the plug-in RAID cards. From some motherboard advertising can be seen, such as the so-called "onboard" RAID chip is the guide bridge to realize the RAID function of the chip. In this way, the operating system does not need to make any changes, in addition to the RAID card driver does not need to install any additional software, you can directly identify the virtual disk has been generated by RAID processing. For software RAID, the operating system to the actual perception in the bottom or at least the physical disk, but for the hardware RAID, the operating system cannot perceive the underlying physical disk, only by the manufacturer to provide a RAID card management software to view your card is connected on a physical disk. Also, when configuring a RAID card, it cannot be done in the operating system, but must be done by entering the hardware (or by using the RAID card configuration tool in the operating system). General RAID card is in the boot self test, into its ROM configuration program to configure a variety of RAID functions. RAID cards overcome the shortcomings of software RAID, so that the operating system itself can be installed on top of the RAID virtual disk, which is not possible with software RAID. Later I will also discuss the relevant knowledge of raid card from multiple dimensions. If you have any questions about storage technology, welcome to consult and answer your questions wholeheartedly. With more than 10 years of professional experience, STOR Technology Limited can also let you experience the original high-performance products at the factory price, such as: megaraid 9460-16i, megaraid 9560-8i, sas 9300-16i and so on. Contact us now！