RAID Levels and Usable Disk Space
Which of the following RAID levels provides fault tolerance with the smallest amount of usable disk space?
Is it RAID 10, RAID 0, RAID 50, or RAID 5?
Answer:
RAID 5 provides fault tolerance with the smallest amount of usable disk space.
RAID 5 is a RAID level that distributes data across multiple disks and stores parity information to provide fault tolerance. In the case of a single disk failure, the parity information is used to recover the data. RAID 5 requires a minimum of three disks to achieve fault tolerance.
Let's compare the usable disk space for different RAID levels using the example of 4 disks, each with a capacity of 1 TB:
1. RAID 10 (Mirrored Stripe):- With 4 disks, RAID 10 will have 2 mirrored sets.
- Usable disk space = Capacity of 2 disks (since the data is mirrored)
- Total usable disk space = 2 TB
2. RAID 0 (Striping):- With 4 disks, RAID 0 will stripe data across all disks without providing fault tolerance.
- Usable disk space = Capacity of all 4 disks
- Total usable disk space = 4 TB
3. RAID 50 (Nested RAID 5):- With 4 disks, RAID 50 combines RAID 5 with striping (RAID 0).
- Usable disk space = Capacity of 2 disks (since RAID 5 provides fault tolerance)
- Total usable disk space = 2 TB
4. RAID 5:- With 4 disks, RAID 5 provides fault tolerance by storing parity information.
- Usable disk space = Capacity of 3 disks (one disk is used for parity)
- Total usable disk space = 3 TB
Among the given RAID levels, RAID 5 provides fault tolerance with the smallest amount of usable disk space. It uses one disk for parity, allowing for the highest level of usable storage space compared to RAID 10 and RAID 50, while still providing fault tolerance in case of a single disk failure. RAID 0 does not offer fault tolerance and uses all disks for data striping, resulting in the highest usable disk space but with no redundancy.