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Raid

In: Computers and Technology

Submitted By jjmess
Words 554
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RAID stands for Redundant Array of Independent Disks. It is a storage technology that combines multiple drive components into a logical unit. Data is distributed across the drives, depending on the level of performance and redundancy required, in one of several RAID levels.
We use RAID when liability and data redundancy are important to you. Even if you take backups, you will need to take the time to restore those backups and those backups could be hours or days old, resulting in data loss. RAID allows you to survive a drive loss without data loss and in many cases without any downtime. RAID is also useful if you are having disk IO issues, where applications are waiting on the disk to perform tasks. Going with RAID will provide you additional throughput by allowing you to read and write data from multiple drives instead of a single drive. There are many types of RAID to choose from depending on what you are looking for. RAID 0 provides improved performance and additional storage but has no redundancy. In RAID 1data is written to two drives producing a mirrored set. This means that the read request is serviced by either of the drives, which contains the data requested. The drive has the least amount of seek time is used. RAID 5 distributes parity along with the data and requires all drives but only needs one to be present to operate. RAID 5 requires at least three disks. This way the array is not destroyed by a single drive failure, and maintains the data. RAID 6 provides fault tolerance up to two failed drives. As large capacity drives lengthen the time needed to recover from a failure on a single drive, this becomes more important. Just like RAID 5, RAID 6 single drive failure results in reduced performance of the entire array until data is rebuilt and the failed drive has been replaced.

Even though RAID 0 offers no redundancy, meaning no backups, it does however improve performance and gives additional storage space through concurrent access and creates large logical disks out of multiple physical disks. RAID 1 can be the most expensive because you need two drives, so purchasing another drive is required. People utilize RAID 1 simply for backup purposes and minimal down time. If I were to purchase a form of RAID for my home personal computer, it would be RAID 1. My reason for this is simple, even though a little more costly it gives me a better backup option for my pc. I did not choose any of the higher RAID levels because I am not storing large amounts of data as would be needed for business purposes. The difference between RAID software and RAID hardware is as follows. First RAID software is implemented in many OS’s as a layer that abstracts multiple devices providing a single virtual device and is a component of the file system. Software RAID also includes Volume manager support, file-system support and OS support. RAID hardware maybe as little as an expansion card, whether internal on the motherboard itself or in a standalone enclosure, and may also be directly attached to a computer or connected via a SAN.

CITED SOURCES: http://searchstorage.techtarget.com/ http://www.pcmag.com/ http://wiki.answers.com/ http://www.pcguide.com/

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