Appendix B: Raid Basics - Thecus N2310 Series Manual Del Usuario

RAID 1 mirrors all data from one hard disk drive to a second one hard disk drive, thus providing com�
plete data redundancy. However, the cost of data storage capacity is doubled.
This is excellent for complete data security.
RAID 5
RAID 5 offers data security and it is best suited for networks that perform many small I/O transactions
at the same time, as well as applications that require data security such as office automation and on�
line customer service. Use it also for applications with high read requests but low write requests.
RAID 5 includes disk striping at the byte level and parity information is written to several hard disk
drives. If a hard disk fails the system uses parity stored on each of the other hard disks to recreate all
missing information.
RAID 6
RAID 6 is essentially an extension of RAID level 5 which allows for additional fault tolerance by using
a second independent distributed parity scheme (dual 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 toler�
ance and can sustain two simultaneous drive failures.
This is a perfect solution for mission critical applications.
RAID 10
RAID 10 is implemented as a striped array whose segments are RAID 1 arrays. RAID 10 has the same
fault tolerance as RAID level 1.
RAID 10 has the same overhead for fault�tolerance as mirroring alone. High I/O rates are achieved by
striping RAID 1 segments.
Under certain circumstances, RAID 10 array can sustain up to 2 simultaneous drive failures
Excellent solution for applications that would have otherwise gone with RAID 1 but need an addi�
tional performance boost.
RAID 50
A RAID 50 combines the straight block�level striping of RAID 0 with the distributed parity of RAID 5.
This is a RAID 0 array striped across RAID 5 elements. It requires at least 6 drives.
RAID 60
A RAID 60 combines the straight block�level striping of RAID 0 with the distributed double parity of
RAID 6. That is, a RAID 0 array striped across RAID 6 elements. It requires at least 8 disks.

Appendix B: RAID Basics

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