Raid Levels

Question 1

Raid 0

Answer 1

Minimum 2 disks.
Excellent performance ( as blocks are striped ).
No redundancy ( no mirror, no parity ).
Don’t use this for any critical system.

Question 2

Raid 1

Answer 2

Minimum 2 disks.
Good performance ( no striping. no parity ).
Excellent redundancy ( as blocks are mirrored ).

Question 3

Raid 5

Answer 3

Minimum 3 disks.
Good performance ( as blocks are striped ).
Good redundancy ( distributed parity ).
Best cost effective option providing both performance and redundancy.
Use this for DB that is heavily read oriented.
Write operations will be slow.

Question 4

Raid 10

Answer 4

Minimum 4 disks.
This is also called as “stripe of mirrors”
Excellent redundancy ( as blocks are mirrored )
Excellent performance ( as blocks are striped )
BEST option for any mission critical applications (especially databases).

Question 5

Raid 6

Answer 5

Provides fault tolerance from two drive failures; array continues to operate with up to two failed drives. This makes larger RAID groups more practical, especially for high availability systems. This becomes increasingly important because large-capacity drives lengthen the time needed to recover from the failure of a single drive. Single parity RAID levels are vulnerable to data loss until the failed drive is rebuilt: the larger the drive, the longer the rebuild will take. Dual parity gives time to rebuild the array without the data being at risk if one drive, but no more, fails before the rebuild is complete.