A system shares 9 tape drives. The current allocation and maximum requirement…
2017
A system shares 9 tape drives. The current allocation and maximum requirement of tape drives for that processes are shown below:
Which of the following best describes the current state of the system?
Answer: B. Safe, Not Deadlocked — Total tape drives = 9 Process Current Allocation Maximum Requirement P1 3 7 P2 1 6 P3 3 5 Step 1: Calculate Available tape drivesTotal…
- A.
Safe, Deadlocked
- B.
Safe, Not Deadlocked
- C.
Not Safe, Deadlocked
- D.
Not Safe, Not Deadlocked
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Show answer & explanation
Correct answer: B
Total tape drives = 9
Process | Current Allocation | Maximum Requirement |
|---|---|---|
P1 | 3 | 7 |
P2 | 1 | 6 |
P3 | 3 | 5 |
Step 1: Calculate Available tape drives
Total allocated=3+1+3=7\text{Total allocated} = 3 + 1 + 3 = 7Total allocated=3+1+3=7Available=9−7=2\text{Available} = 9 - 7 = 2Available=9−7=2
Step 2: Calculate Need = Max − Allocation
Process | Need |
|---|---|
P1 | 7−3=47 - 3 = 47−3=4 |
P2 | 6−1=56 - 1 = 56−1=5 |
P3 | 5−3=25 - 3 = 25−3=2 |
Step 3: Check for a safe sequence
Available = 2
✔ P3 can complete (needs 2)
→ releases 3 → Available = 5
✔ P1 can now complete (needs 4)
→ releases 3 → Available = 8
✔ P2 can now complete (needs 5)
→ releases 1 → Available = 9
Safe sequence exists: P3 → P1 → P2
✅ Final Answer
The system is in a SAFE STATE (not deadlocked and deadlock-free at present).
Best description:
✔ The system is in a safe state.
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