Rocstor GUARDIAN 4RT, Installation And Configuration Manual

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ROCSECURE – Guardian 4RT Secure Raid System User Manual Page | 107
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 or 1+0.
Summary
RAID 0 is the fastest and most efficient array type but offers no fault-tolerance. RAID 0
requires a minimum of one drive.
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.
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.
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.
RAID Management
The user can implement several different levels of RAID technology. RAID levels supported are
shown below.
RAID Level Description Min. Drives
0
Block striping is provided, which yields higher
performance than with individual drives. There is
no redundancy.
1
1
Drives are paired and mirrored. All data is 100%
duplicated on an equivalent drive. Fully
redundant.
2
3
Data is striped across several physical drives.
Parity protection is used for data redundancy.
3
5
Data is striped across several physical drives.
Parity protection is used for data redundancy.
3
1 + 0
Combination of RAID levels 0 and 1. This level
provides redundancy through mirroring and
striping.
4