07a40502-operatingsystems

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Code No: 07A40502 R07 Set No. 2

II B.Tech II Semester Regular/Supplementary Examinations,May 2010OPERATING SYSTEMS

Information TechnologyTime: 3 hours Max Marks: 80

Answer any FIVE QuestionsAll Questions carry equal marks

1. (a) Explain in detail about Hydra.

(b) Write short notes on the following:

i. One-time passwords

ii. Biometrics. [8+8]

2. (a) Describe the data structures to be maintained for implementing the Bankersalgorithm.

(b) Explain the following:

i. Polling

ii. Interrupts. [6+10]

3. (a) What is memory fragmentation? Explain the difference between external andinternal fragmentation.

(b) Write about the typical instruction cycle.

(c) What are logical address and physical address. [5+5+6]

4. (a) How dual mode operation of an operating system ensures protection.

(b) What are the uses of timer for the operating system? [8+8]

5. (a) What are the advantages and disadvantages of recording the name of thecreating program with the files attributes?

(b) Explain about the layered file system with a neat diagram. [8+8]

6. (a) What is the syntax of a monitor.

(b) What is the use of condition construct of a monitor. [8+8]

7. (a) Explain the layers at which RAID can be implemented.

(b) What is stable storage? Explain how it is implemented. [8+8]

8. (a)What are the system calls associated with process? (b) Differentiate between process and thread. [10+6]

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1. Define semephore. Write prodecure-consumer problem and the structure of producer and consumer processes using semephores. [16]

2. How do you establish a relationship between user thread and kernel thread? What

is the functions provided in thread library?

3. (a) Why an operating system is called a resource allocator. How it allocatesresources.

(b) Define an operating system. [12+4]

4. (a) What is the formula for effective access time of a page.

(b) What are the protection bits associated with paging. How they are useful inproviding protection.

(c) How pages are shared. [5+5+6]

5. (a) Give an example of an application that could benefit from OS support forrandom access to indexed files.

(b) Explain in detail the different methods of implementing directories. [8+8]

6. (a) Give a detailed note on the flexible capability-based protection system Hy-dra

(b) Explain in detail about the windows XP security model. [8+8]

7. (a) Consider the following snapshot of a systemAllocation Max AvailableA B C D A B C D A B C D

P0 0 3 1 2 0 0 1 2 1 5 2 0P1 1 0 0 1 1 7 5 0P2 1 3 5 4 2 3 5 6P3 0 6 3 2 0 6 5 2P4 0 0 1 4 0 6 5 6

Answer the following questions using the Bankers algorithm:

i. What is the content of the matrix need ?

ii. Is the system in a Safe State?

iii. If a request from process P1arrives for (0,4,2,0), can the request be granted

immediately ?

(b) Illustrate with a diagram how the I/O-related portions of the kernel are struc-tured in software layers. [10+6]

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8. (a) Why is it difficult to map a logical block number onto the sectors of the disk?

(b) Explain the following RAID levels with diagrams.i. Memory-style error-correcting code organization

ii. Bit-interleaved parity organization

iii. Block-interleaved parity organization. [6+10]

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1. Explain the locking protocol for serializability. [16]

2. (a) What is a file? What are the typical attributes of a file?

(b) Write a note on file-system mounting. [8+8]3. (a) Discuss about the domain of protection.

(b) Give a detailed note on user authentication. [6+10]

4. (a) Compare shared memory system with message passing system giving theirrelative advantages and disadvantages.

(b) Illustrate them with examples. [8+8]

5. With an example show that SSTF algorithm is a substantial improvement over theFCFS algorithm. [16]

6. Explain different techniques in which a process is allocated memory wherever it isavailable with an example. [16]

7. (a) Consider the following snapshot of a systemAllocation Max Available

P1 A B C A B C A B CP2 3 1 0 7 5 3 3 3 2P3 2 0 1 3 2 4P4 3 0 2 9 0 2P5 2 0 2 4 3 3

Answer the following questions using the Bankers algorithm:

i. What is the content of the matrix need?

ii. Is the system in a Safe State?

iii. If a request from process P0arrives for (0,2,0), can the request be grantedimmediately ?

(b) What is polling? What are its advantages and disadvantages? [10+6]

8. The issue of resource utilization shows up in different forms in different types ofoperating systems. List what resources must be managed carefully in the following

settings:(a) Mainframe or minicomputer systems.

(b) Workstations connected to servers

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(c) Handheld computers. [6+5+5]

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1. What is critical section problem? What is the solution for it? Explain it with anexample. [16]

2. (a) Explain the computer system operation.

(b) What is the hierarchy of storage devices? [8+8]

3. Write briefly about

(a) external fragmentation:

(b) Internal fragmentation

(c) 50-percent rule

(d) Compaction. [4+4+4+4]

4. (a) Draw the resource-allocation graph with a deadlock and explain?

(b) What are the various kinds of performance overheads associated with servicingan interrupt? [8+8]

5. (a) How can systems that implement the principle of least privilege still haveprotection failures that lead to security violation?

(b) Discuss about the following:

i. Viruses

ii. Stack and buffer overflow. [6+10]

6. (a) Discuss the problems with RAID.

(b) Write brief notes on:i. Network-attached storage

ii. Storage-area network. [6+10]

7. How RMI is used for communication. [16]

8. (a) a) Some systems automatically open a file when it is referenced for the firsttime and close the file when the job terminates. Discuss the advantages anddisadvantages of this scheme compared with the more traditional one wherethe user has to open and close the file explicitly.

(b) Give a detailed description of standard Linux file system -ext2fs. [8+8]

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