📖 What is RAID 5 (Redundant Array of Independent Disks 5)?
RAID 5 (Redundant Array of Independent Disks 5) uses block-level striping with distributed parity across three or more disks. This configuration balances performance and redundancy, allowing the array to survive the failure of a single drive without data loss.
"You need at least three disks for RAID 5. Remember that 'parity' is the key word for this specific level of redundancy."
📚 Certification: CompTIA A+ Certification Exam Core 1 (220-1101)
🔑 What are the Key Concepts of RAID 5 (Redundant Array of Independent Disks 5)?
- ▸ Requires a minimum of three physical disks to function, providing a balance between storage capacity, performance, and fault tolerance.
- ▸ Utilizes distributed parity, meaning redundancy data is spread across all drives rather than being stored on a single dedicated disk.
- ▸ Offers fault tolerance for a single drive failure; if one disk fails, the array remains operational and data can be reconstructed.
- ▸ Provides improved read performance through striping, though write performance is slightly reduced due to the overhead of calculating parity.
- ▸ Calculates usable capacity as the total number of disks minus one, multiplied by the size of the smallest drive in the array.
🎯 How does RAID 5 (Redundant Array of Independent Disks 5) appear on the 220-1101 Exam?
You may be asked to recommend a RAID level for a small business server that requires a balance of read performance and redundancy using three available hard drives.
A scenario might describe a server where one disk has failed, but the system is still running. You will need to identify this as RAID 5 and suggest replacing the drive.
Expect questions where you must distinguish RAID 5 from RAID 1 or RAID 10 based on the number of disks provided and the specific redundancy requirements.
❓ Frequently Asked Questions
How does RAID 5 differ from RAID 1?
RAID 1 uses mirroring, requiring only two disks and duplicating all data. RAID 5 uses striping with parity across three or more disks, offering more usable storage space than mirroring while still providing fault tolerance.
What happens if two drives fail simultaneously in a RAID 5 array?
If two or more drives fail, the array collapses and all data is lost. RAID 5 can only sustain the loss of one single drive before the parity information becomes insufficient for reconstruction.
Why is RAID 5 considered slower for write operations than RAID 0?
RAID 0 simply writes data across disks. RAID 5 must calculate parity information for every write operation and distribute it across the array, creating a computational overhead known as the write penalty.