PrepSnap logoPrepSnap
Pass

Question

1.
2.
3.
4.
Answer (Detailed Solution Below)

Option 2 : D2 = D1 XOR D3 XOR P, solving the parity equation for the missing term

Advertisement

Detailed Solution

सही उत्तर D2 = D1 XOR D3 XOR P, solving the parity equation for the missing term है।

Key Points
Helpful?
PrepSnapprepsnap.in • Part -A

Question:

In a RAID 5 array, data disks hold D1, D2, D3 and parity P equals D1 XOR D2 XOR D3. Disk 2 fails completely. How is D2 reconstructed? / RAID 5 ऐरे में डेटा डिस्क पर D1, D2, D3 हैं और parity P = D1 XOR D2 XOR D3 है। डिस्क 2 पूर्णतः विफल हो गई। D2 का पुनर्निर्माण कैसे होगा?

1.
D2 = D1 XOR D2 XOR D3, reusing the failed disk's last known value
2.
D2 = D1 XOR D3 XOR P, solving the parity equation for the missing term
3.
D2 = P alone, because parity is a complete copy of each data disk
4.
D2 cannot be reconstructed; RAID 5 only speeds up reads

Correct Answer: D2 = D1 XOR D3 XOR P, solving the parity equation for the missing term

XOR is its own inverse, so the missing term is recovered as D1 XOR D3 XOR P — the fundamental RAID 5 rebuild equation. / XOR अपना प्रतिलोम है, इसलिए लापता पद D1 XOR D3 XOR P से निकलता है — यही RAID 5 पुनर्निर्माण समीकरण है। Option (c) is the trap — parity is a checksum-like combination, not a copy.

Downloaded from PrepSnap (prepsnap.in)