SAN School Answer #6 |
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By SearchStorage.com editors
13 Aug 2003 | SearchStorage.com |
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SAN School Answer #6
Question #6
This is a way of storing the same data in different places (redundantly) on multiple hard disks.
a. data mining
b. disk duplexing
c. RAID
d. data splitting
e. virtualization
The correct answer is:
c. RAID
Learn more:
RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O operations can overlap in a balanced way, improving performance. Since multiple disks increases the mean time between failure (MTBF), storing data redundantly also increases fault-tolerance.
A RAID appears to the operating system to be a single logical hard disk. RAID employs the technique of striping, which involves partitioning each drive's storage space into units ranging from a sector (512 bytes) up to several megabytes. The stripes of all the disks are interleaved and addressed in order.
In a single-user system where large records, such as medical or other scientific images, are stored, the stripes are typically set up to be small (perhaps 512 bytes) so that a single record spans all disks and can be accessed quickly by reading all disks at the same time.
In a multi-user system, better performance requires establishing a stripe wide enough to hold the typical or maximum size record. This allows overlapped disk I/O across drives.
For more on RAID, see also:
RAID reliability
Selecting the proper RAID level for your business intelligence workload
Setting up databases, indexes and log files
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