RAID Levels

In 1988 the first RAID (Redundant Array of Independent Disks) was conceived and implemented. The RAID concept allows multiple hard disk drives to be used for the purposes of providing redundancy and allowing them to be configured as a larger capacity storage device. When redundancy is employed within a RAID it decreases the risk of losing data in the event of a hard disk drive failure at a reduction in total capacity. In some cases the configuration can also result in improved data transfer speeds.

With the large quantities of data which need to be stored, larger volumes are becoming increasingly important. This does however, come with some element of risk, so it is vitally important to implement the correct RAID architecture in order to decrease the possibility of data loss. Our data recovery specialists have recovered data from a vast range of RAID systems, the vast majority of which have failed due to hardware failure of the hard disk drives.


Commonly called striping with distributed or rotating parity, RAID 5 distributes the parity data across all the drives, which ensures that no single disk is devoted to storing the parity. This is still one of the favourite choices for creating a large storage space in server and data processing systems, as it gives an excellent compromise between data security and speed. The distributed parity allows the RAID array to operate in degraded form in the event of a single drive failing. Recovery from failed RAID 5 arrays is our most commonly required RAID recovery solution.


Commonly known as striping with dedicated parity, RAID Level 3 uses one dedicated disk in the array for storing the parity data. Like RAID 5 this type of array gives a good compromise between security and data transfer speed, with the ability to continue running in degraded mode when one disk fails. the data, can be rebuilt from the parity drive. This type of RAID is now rarely used, usually only seen in older systems.


Commonly called mirroring, RAID Level 1 duplicates all the data of one disk, to the other drive in order to provide 100 percent redundancy. This type of array performs slightly better than a single drive and is capable of operating when one of the two suffers a failure. Once one drive fails, it is important to re-mirror the data as a subsequent failure will cause the array to fail. Data recovery from this type of array is becoming increasingly common, mainly due to the increased uptake of using a mirrored array, particularly for server systems.


Known as data striping, RAID 0 spreads the data across two or more hard disk drives, which results in an increased data throughput. The lack of calculating redundancy allows for a significant improvement when writing data over other types of RAID. It is still a popular configuration, despite providing no redundancy meaning that the array will fail if even a single drive suffers a failure. This type of array should only be used in combination with a regular backup strategy when the increased data throughput is essential. The risk of data loss is therefore increased significantly due to the lack of redundancy. Despite this, the success rate for recovering data from this type of array is high.

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