Articles
If you have configured your computer with RAID system, data recovery is also possible.
Victim of broken raids, you can recover data by using the RAID reconstructor. Even if you do not know the RAID parameters, such as start sector, drive order, block size and direction of rotation, RAID reconstructor will examine your drives and determine the correct values. You will then be able to make a copy of the reconstructed RAID in a virtual image (.vim), an image file (.img) or on a physical drive. There are three key concepts in RAID. These are mirroring, striping and error connection.
Mirroring is the writing of identical data to more than one disk. Stripping is the splitting of data across more than one disk. Error connection is where redundant parity data is stored to allow problems to be detected and possibly repaired which is known as fault tolerance. Depending on the system requirements, different RAID schemes use one or more of these techniques. The aim of using RAID is to ameliorate reliability and availability of data, ensuring that important data is not harmed in case of hardware failure, and/or to increase the speed of file input or output.
Each RAID scheme affects reliability and performance in various ways. Every additional disk included in an array adds up the likelihood that one will fail, but by using error checking or mirroring, the array as a whole can be made more trusted by the ability to survive and recover from a failure. Mirroring can speed up the reading of data, as a system can construe different data from multiple disks at the same time, but it may be slow for writing if the configuration asks that all disks must corroborate that the data is correctly written. Striping, often used for increasing performance, writes each bit to a different disk, allowing the data to be rebuilt from multiple disks faster than a single disk could send the same data. Error checking typically will slow down performance as data needs to be read from different places and then compared. Modern disk arrays typically provides the facility to select an appropriate RAID configuration.
When you encounter a RAID that is broken, Systems with redundancy continue working without interruption when one (or possibly more, depending on the type of RAID) disks of the array is no longer functioning, although they are then vulnerable to further failures. When the bad disk is renewed, the array is rebuilt while the system continues to operate normally. Hot swapping is one of the ways of support, which replaces components without significant interruption to the system. Equipment like the RAID disk arrays allows a faulty disk to be hot-swapped for a new one; the new one is configured to become part of the array automatically or by user command.
Using a special hardware or software, RAID unites two or more physical hard disks into a single logical. Hardware solutions are often made to present themselves to the attached system as a single hard drive, so that the operating system would be unaware of the technical workings. For example, if one were to configure a hardware-based RAID-5 volume using three 250 GB hard drives, the operating system would be presented with a single 500 GB volume. Software solutions are typically applied in the operating system and would present the RAID volume as a single drive to applications running within the operating system.
Arranging disks into a redundant array decreases the usable storage capacity. For instance, a 2-disk RAID 1 array loses half of the total capacity that would have otherwise been accessible using both disks independently, and a RAID 5 array with several disks loses the capacity of one disk. Other types of RAID arrays are organized, for example, so that they are faster to write to and read from than a single disk.
There are different combinations of these approaches giving various trade-offs of protection against data loss, capacity, and speed. RAID levels 0, 1, and 5 are the most commonly opened, and cover most requirements. RAID can involve important computation when reading and writing information. In other cases the operating system or simpler and less expensive controllers needs the host computer's processor to do the computing, which decreases the computer's performance on processor-intensive tasks. Simpler RAID controllers may provide only levels 0 and 1, which needs less processing.
Remote Data Backup :: Data Backup Storage :: Backing Up Desktop :: Travan Tape Backup
Home :: Backup Online :: Backup Image :: Backup Computer :: Backup Tapes
DVD Backup :: Data Recover :: External Backup Devices :: SAN :: NAS :: Disk Mirroring
Site Map :: Articles :: Blog :: Contact Us :: Link to Us :: Links
