Developed in the early 80's, RAID technology is used to improve performance and fault tolerance. RAID 5, which is one of the most commonly used RAID systems, provides both security and performance and is based on at least three hard drives.

RAID 5 technician

RAID 5: what to you need to understand

First of all, you have to understand that a RAID system is the use of multiple hard drives as a single entity. The term RAID, first introduced in the second half of the 1980s, means Redundant Arrays of Inexpensive Disks. The goal, above all, is to use commercially available, but fault-tolerant, low-performance hard drives, in order to deal with the main defects while spending as little as possible. Of the major RAID technologies used, RAID 0, RAID 1 and RAID 5 are the most commonly used.

  • RAID 5 uses at least three hard drives and strips data across multiple hard drives to improve performance through simultaneous access, but unlike RAID 0, RAID 5 includes correction codes (parity bits) between the data.

  • RAID 0 is based on stripping techniques of interspersed data between multiple hard drives to provide increased performance. Used on a minimum of two disks, the RAID 0 divides the data into tapes and distributes them on the various available storage units. Since data access is done on multiple disks at the same time, the speed is increased, but the lack of redundancy does not give it greater fault tolerance. This is the favourite RAID system of hardcore gamers.

  • RAID 1 is particularly simple to understand as it mirrors the contents of a hard drive on another that will serve for failure security. The gain in speed is nonetheless non-existent. This RAID system is the solution for individuals and businesses that store sensitive data without the need for performance.

The operation of RAID 5

Like any RAID system, RAID 5 uses multiple hard drives clustered together to form a single logical drive. In the RAID 5 system, the data is divided into a minimum of three hard disks to a maximum of sixteen. Unlike RAID 0, the data is interspersed with parity bits in case of the event of a hard disk failure. The parity bits are inserted after a sequence of saved data and are distributed on all the disks.

RAID 4, which also uses the parity bits, concentrates them on a single hard disk. In the event of a hard disk failure, the risk of data loss is low. If data is damaged, the previous bits and the parity block make it possible to recover the lost data. If the parity bit is damaged, the data is intact and therefore accessible without problems. Since after a number of disks, a parity bit is written, the space actually available on N disk number is N-1. For example, on five 500GB disks that offer a total of 2.5TB of space, only 2TB is available.

What’s the best RAID system for you?

RAID 5 is one of the most used systems because of its performance and promise of security. It should be noted, however, that other RAID types have their own characteristics that each respond to a specific need.

Before choosing, ask yourself the right questions. Would you like to increase the security of your data? Do you want to increase the performance of your hard drive or do you want a greater fault tolerance?

RAID 5 vs RAID 6

Like RAID 5, RAID 6 has a parity distribution. Both systems work the same way. The RAID 5 is particularly known for its high performance and its tolerance to breakdowns. In addition, your data is protected in the event of a failure, provided that the failure is on a single disk.

When data loss occurs on a single disk, the data remains accessible but there will be a drop in performance until the missing data is restored. On the other hand, if the failure concerns over several disks, the data will be lost. This is where you will find all the advantages of a RAID 6 - it is able to keep all of your data even if two disks fail. One disadvantage is that RAID 6 is slower than RAID 5.

RAID 5 vs RAID 1

RAID 1 and RAID 5 both provide excellent fault tolerance. Thanks to the mirroring system, RAID 1 works by duplication and offers redundant storage, which improves the security of your data.

RAID 1 is composed of two disks; when the data is written on one, it is copied onto the other. If a drive fails, all of your data will be available on the second drive. RAID 5 requires a minimum of 3 drives, and will recover data if one drive fails, but compared to RAID 1, RAID 5 offers greater write performance.

RAID 5 or RAID 10

RAID 10 or RAID 1 + 0 is the combination of the RAID 1 system and the RAID 0 system. The RAID 10 consists of at least 4 storage units and is characterised by increased reliability. With RAID 5, a single failed drive does not lose data, but if two drives fail, the data is lost. With a RAID 10, if a drive fails, the entire system remains functional and data integrity is available. The RAID 10 meets the needs of reliability but also of high performance.

What is RAID 5 spare?

As a reminder, the RAID 5 requires a minimum of 3 hard drives. The RAID 5 spare has 4 disks; the fourth unit being used as a spare. This guarantees the safety of your data, with the spare only being used when one of the disks fails. In short, the RAID 5 spare meets your needs if you want to benefit from increased security.

RAID 5 capabilities

RAID 5 makes it possible to simultaneously use all its disks (this one consists of at least 3 disks). It is a high-performance system for reading and writing and offers great fault tolerance.

The RAID 5 also offers a high capacity equivalent to N-1, where N is the total number of disks. The effective usable capacity of RAID 5 is the total capacity of all units minus the capacity of a hard drive.

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