What is the difference between hard and soft raid?

What is RAID?

RAID is an abbreviation for the English Redundant array of independent disks, which translates into Chinese as a redundant array of independent disks, or simply a disk array. Simply put, RAID is a technology that combines multiple separate hard disks (physical hard disks) into a single hard drive group (logical hard disk) in a different way, providing higher storage performance and data redundancy than individual drives. The different ways to make up a disk array are RAID levels (RAID levels).

　　Why do we use RAID?

　　

People who need to keep large amounts of data on their hard disks, such as an ordinary administrator, will be able to use RAID technology. The main reasons for using RAID are:

· Increase the speed

· Increased storage capacity (and more convenience)

· Efficient Recovery Disk

　　Hard raid differs from soft raid:

　　What is hard raid?

Using hardware to implement RAID features is hard raid, such as: A variety of RAID cards, as well as the motherboard integration to do raid is hard raid.

　　What is soft raid?

Using the operating system to complete the RAID function is soft raid, such as: Under the Windows2000 operating system, with three hard disk to do the RAID5.

　　First, performance
This is probably the most important aspect of using RAID to improve performance. Theoretically, using RAID0 can be used to double the speed of a single disk drive, with soft/hard RAID0 can be approached at this speed. With soft raid, the CPU usage is higher, so hard raid is the leading performance.

　　Second, stability

RAID is for performance, so you typically use a 7200rpm hard drive. The market on the mainstream 7200rpm hard disk heat is generally large, while in the chassis put two, cooling is already a problem, let alone three pieces. After all, stability is overriding, and if the hard drive is burnt it will not outweigh the gains. Moreover, some chassis do not put three hard drives at all. Therefore, the stability of using hard raid is higher.

　　Third, the operation of simple
implementing raid in windows2000/2003 takes only a few simple steps, and the entire interface is in Chinese, even for people who don't know much about raid. If you are using the external RAID card, the operation is much more troublesome, the operating interface is in English, can not use the translation software, so soft raid to achieve more simple.

　　Iv. compatibility
until now, only windows2000/2003 supports soft raid. This means that if you use soft raid, then you have to give up win9x/winme/linux and so on. Hard raid compatibility is better and can even be compatible with DOS. If Windows is out of the question, it is much easier to do system maintenance.

　　Five, security
soft raid security is bad, when a hard disk is damaged, it does not achieve the function of rebuilding, and its limitations are also very good, and hard raid when hard disk is lost, it can be rebuilt, and if the raid card is damaged, it can be replaced by the raid card to achieve the ability to do not lose data.

　　Difference between motherboard integrated RAID and external raid card raid:

　　First, performance
Motherboard integrated RAID, its performance and its speed is through the motherboard CPU and memory to achieve, it will occupy the motherboard a certain bandwidth, will affect the performance of the whole machine, and plug the Raid card, it itself has its own CPU and memory, so it's data processing most of it will be handled by themselves, The CPU and memory speeds on the motherboard are not affected, and in general, the raid on the outer-inserted RAID card is much faster than the motherboard-integrated raid.

　　Second, security
Motherboard Integrated RAID its security is not guaranteed, such as: we use the P8SCT motherboard to do a SATA raid, no matter what you do raid, it is made by changing the motherboard BIOS options, so once the motherboard is damaged, the motherboard's CMOS battery power off, Inadvertently changing the motherboard BIOS settings will bring raid loss, through the motherboard raid, once lost, will be unable to recover, the consequences are very serious, and the raid card made by the raid will not be due to damage to the motherboard, the motherboard of the CMOS battery power off, and other phenomena affecting the data, So the external RAID card, which is much more secure than the motherboard integration.

　　Conclusion: in choosing that Raid form, the first is based on the customer's demand, the price of the machine and what the client is ultimately doing, depending on the situation.