To offer superior quality of service, WebTop offers RAID 10 redundancy (offering both RAID 1 and RAID 0 as depicted) on their hosting servers to give you peace of mind that your data is both safe, secure, and highly accessible to you and your business.
RAID stands for describe a Redundant Array of Inexpensive Disks, a technology that allowed computer users to achieve high levels of storage reliability from low-cost and less reliable PC-class disk-drive components, via the technique of arranging the devices into arrays for redundancy.
Redundancy is achieved by either writing the same data to multiple drives (known as mirroring), or writing extra 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. Organizing 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 available using both disks independently, and a RAID 5 array with several disks loses the capacity of one disk. Other types of RAID arrays are arranged so that they are faster to write to and read from than a single disk.
There are various combinations of these approaches giving different trade-offs of protection against data loss, capacity, and speed. RAID levels 0, 1, and 5 are the most commonly found, and cover most requirements.
RAID can involve significant computation when reading and writing information. With traditional "real" RAID hardware, a separate controller does this computation. In other cases the operating system or simpler and less expensive controllers require the host computer's processor to do the computing, which reduces the computer's performance on processor-intensive tasks. Simpler RAID controllers may provide only levels 0 and 1, which require less processing.
RAID systems with redundancy continue working without interruption when one (or possibly more, depending on the type of RAID) disks of the array fail, although they are then vulnerable to further failures. When the bad disk is replaced by a new one the array is rebuilt while the system continues to operate normally. Some systems have to be powered down when removing or adding a drive; others support hot swapping, allowing drives to be replaced without powering down. RAID with hot-swapping is often used in high availability systems, where it is important that the system remains running as much of the time as possible.
RAID is not a good alternative to backing up data. Data may become damaged or destroyed without harm to the drive(s) on which they are stored. For example, part of the data may be overwritten by a system malfunction; a file may be damaged or deleted by user error or malice and not noticed for days or weeks; and, of course, the entire array is at risk of physical damage.
Posted Tuesday, 19 October 2010 at 05:58 by Andrew Liu
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