RAID Levels Questions with complete
solution 2025/2026
Redundant Array of Independent Disks (RAID) - correct answer ✔A technique that combines multiple
disk drives into a logical unit (RAID set) and provides protection, performance, or both. Can be hardware
or software implementation.
RAID 0 - correct answer ✔Uses striping, provides all performance and no fault tolerance.
RAID 1 - correct answer ✔Uses mirroring, provides fault tolerance. Data is duplicated.
Every write manifests as two I/O operations (2 disk writes)
RAID 1+0 - correct answer ✔Nested RAID - Uses both striping and mirroring to provide fast
performance as well as fault tolerance. Most expensive, requires the most storage.
RAID 3 - correct answer ✔Striped set with parallel access and dedicated parity disk. Old technology,
strange, and specific.
Only useful for LARGE sequential I/O (backups, etc.)
RAID 5 - correct answer ✔Striped set with independent disk access and a distributed parity. Parity cost
is one disk.
Every write from a host manifests as four I/O operations (2 disk reads, 2 disk writes)
RAID 6 - correct answer ✔Striped set with independent disk access and dual distributed parity. Can
support two spindle failures, but is generally not used in practice.
solution 2025/2026
Redundant Array of Independent Disks (RAID) - correct answer ✔A technique that combines multiple
disk drives into a logical unit (RAID set) and provides protection, performance, or both. Can be hardware
or software implementation.
RAID 0 - correct answer ✔Uses striping, provides all performance and no fault tolerance.
RAID 1 - correct answer ✔Uses mirroring, provides fault tolerance. Data is duplicated.
Every write manifests as two I/O operations (2 disk writes)
RAID 1+0 - correct answer ✔Nested RAID - Uses both striping and mirroring to provide fast
performance as well as fault tolerance. Most expensive, requires the most storage.
RAID 3 - correct answer ✔Striped set with parallel access and dedicated parity disk. Old technology,
strange, and specific.
Only useful for LARGE sequential I/O (backups, etc.)
RAID 5 - correct answer ✔Striped set with independent disk access and a distributed parity. Parity cost
is one disk.
Every write from a host manifests as four I/O operations (2 disk reads, 2 disk writes)
RAID 6 - correct answer ✔Striped set with independent disk access and dual distributed parity. Can
support two spindle failures, but is generally not used in practice.
