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RAID level 1 uses at least two duplicate hard drives and store the exact same
blocks of information between them. This is the slowest form of fault
tolerance because the data has to be replicated onto two disks at the same
time. However, this is the simplest way to provide high reliability.
If one of the mirrored drives suffers a mechanical failure or does not respond,
the remaining drive will continue to serve and provide correct data. If one
drive has a physical sector error, the mirrored drive will continue to function.
Due to redundancy, the drive capacity of the array is half the total drive
capacity. For example, two 40GB drives that have a combined capacity of
80GB would have 40GB of usable storage. With drives of different capacities,
there may be unused capacity on the larger drive. RAID 1 increases cost as it
takes twice as much hard drives to build our arrays.
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Logical Drive
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Physical Disks
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