RAID Data Recovery involves the use of multiple hard disk drives that divide and replicate computer data. Like a insurance policy the different RAID schemes spread the risk of data loss over several disks insuring that the failure of one disk does not result in irretrievable loss – a simple idea that is technically complex.
RAID’s main aim can be either to improve reliability and availability of data, or merely to improve the access speed to files.
Three Key Concepts of RAID Data Recovery:
Basic mirroring can speed up reading data as a system can read different data from both the disks, but it may be slow for writing if the configuration requires that both disks must confirm that the data is correctly written.
Striping is often used for performance, where it allows sequences of data to be read from multiple disks at the same time. Error checking typically will slow the system down as data needs to be read from several places and compared.
Redundancy is achieved by either writing the same data to multiple drives (known as mirroring), or collecting data (known as parity data) across the array, calculated such that the failure of one (or possibly more, depending on the type of RAID) disks in the array will not result in loss of data. A failed disk may be replaced by a new one, and the lost data reconstructed from the remaining data and the parity data.
Different RAID levels use one or more of these techniques, depending on the system requirements.
The design of RAID systems is therefore a compromise and understanding the requirements of a system is important. Modern disk arrays typically provide the facility to select the appropriate RAID configuration.
The configuration affects reliability and performance in different ways. The problem with using more disks is that it is more likely that one will fail, but by using error checking the total system can be made more reliable by being able to survive and repair the failure.
data recovery services, with no dedicated parity drive write performance, is better than RAID 3 with overlapped data and parity update writes.
RAID 1 performs faster but RAID 5 provides better storage efficiency. Parity update can be more efficiently handled by RAID 5 by checking for data bit changes and only changing the corresponding parity bits.
For small data writes improvements here are lost as most disk drives update sectors entirely for any write operation. For larger writes only the sectors where bit changes need to be made are rewritten and improvements made.
In some cases, maintaining parity information reduces write performance as much as one third the speed of RAID 1. For this reason RAID 5 is not normally used in performance critical processes.
The main reason for the use of RAID disks is to improve data integrity and performance. By saving data on multiple drives, you essentially improve the possibility of data recovery and make the process of data storage faster than if saved on one, single hard drive.