Proware DP-503-F4A3, Инструкция по установке и эксплуатации

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DP-503-F4A3 RAID SUBSYSTEM
16 Installation and User Manual
main advantage of RAID 6 is High data availability – any two drives can fail without loss of critical
data.
Dual-level RAID achieves a balance between the increased data availability inherent in RAID 1 and
the increased read performance inherent in disk striping (RAID 0). These arrays are sometimes
referred to as RAID 0+1.
In summary:
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RAID 0 is the fastest and most efficient array type but offers no fault-tolerance. RAID 0 requires a
minimum of one drive.
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RAID 1 is the best choice for performance-critical, fault-tolerant environments. RAID 1 is the only
choice for fault-tolerance if no more than two drives are used.
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RAID 3 can be used to speed up data transfer and provide fault-tolerance in single-user
environments that access long sequential records. However, RAID 3 does not allow overlapping of
multiple I/O operations and requires synchronized-spindle drives to avoid performance
degradation with short records. RAID 5 with a small stripe size offers similar performance.
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RAID 5 combines efficient, fault-tolerant data storage with good performance characteristics.
However, write performance and performance during drive failure is slower than with RAID 1.
Rebuild operations also require more time than with RAID 1 because parity information is also
reconstructed. At least three drives are required for RAID 5 arrays.
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RAID 6 is essentially an extension of RAID level 5 which allows for additional fault tolerance by
using a second independent distributed parity scheme (two-dimensional parity). Data is striped on
a block level across a set of drives, just like in RAID 5, and a second set of parity is calculated
and written across all the drives; RAID 6 provides for an extremely high data fault tolerance and
can sustain multiple simultaneous drive failures. It is a perfect solution for mission critical
applications.
RAID Management
The subsystem can implement several different levels of RAID technology. RAID levels supported by