1. What is RAID?
A) RAID (Redundant Array of Independent/Inexpensive Disks) is a technology that combines multiple physical disks into a single logical unit for improved performance, redundancy, or both.
2. What are the different RAID levels?
A) Common RAID levels include:
- RAID 0 (Striping)
- RAID 1 (Mirroring)
- RAID 5 (Striping with Parity)
- RAID 6 (Double Parity)
- RAID 10 (Combination of RAID 1 and 0)
Others include RAID 2, 3, 4, 50, 60.
3. What is RAID 0?
A) RAID 0 uses disk striping without redundancy. It improves performance but does not provide fault tolerance. Failure of one disk results in total data loss.
4. What is RAID 1?
A) RAID 1 mirrors data across two or more disks. It provides redundancy and high availability but reduces usable storage to 50%.
5. What is RAID 5?
A) RAID 5 stripes data with parity across three or more disks. It offers both fault tolerance (can survive one disk failure) and good read performance.
6. What is RAID 6?
A) RAID 6 is like RAID 5 but with double parity. It can tolerate two simultaneous disk failures, but write performance is slower due to extra parity calculation.
7. What is RAID 10 (1+0)?
A) RAID 10 is a combination of RAID 1 (mirroring) and RAID 0 (striping). It provides high performance and fault tolerance but requires at least 4 disks.
8. Difference between hardware RAID and software RAID?
A)
- Hardware RAID: Managed by a RAID controller card, better performance, costlier.
- Software RAID: Managed by the operating system, cheaper but slower.
9. What are hot spare disks?
A) A hot spare is an idle disk in a RAID array that automatically replaces a failed disk to rebuild data without manual intervention.
10. Which RAID level offers best performance?
A) RAID 0 offers best performance since it uses striping, but it provides no redundancy.
11. Which RAID level is best for databases?
A) RAID 10 is commonly used for databases because it provides both performance (striping) and redundancy (mirroring).
12. What is parity in RAID?
A) Parity is a calculated value used in RAID (5, 6) that allows data to be reconstructed if a disk fails.
13. What is the minimum number of disks required for RAID 5?
A) RAID 5 requires at least 3 disks.
14. Which RAID is most cost-effective?
A) RAID 5 is considered most cost-effective as it provides a balance between performance, redundancy, and storage efficiency.