A processor sends 40 disks I/Os per second, these requests areexponent-distributed, and the average service time of an olderdisk is 20 ms. Answer the following questions:1. On average, how utilized is the disk?2. What is the average time spent in the queue?3. What is the average response time for a disk request,including the queuing time and disk service time?

Answered: A processor sends 40 disks I/Os per…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Consider a file system on a disk that has both logical and physical block sizes of 512 bytes. Assume that the information about each file is al ready in memory. For each of the three allocation strategies (contiguous, linked, and indexed), answer these questions: a. How is the logical-to-physical address mapping accomplished in this system? (For the indexed allocation, assume that a file is always less than 512 blocks long.) b. If we are currently at logical block 10 (the last block accessed was block 10) and want to access logical block 4, how many physical blocks must be read from the disk
Calculate the number of disk tracks traversed using the SSTF algorithms for the series of disk track service requests given as 54,36,21,74,46,35,26,67. At the time the first request arrives in the disk request queue, the read/write head is at track 50, moving toward the outer (lower-numbered)tracks. Draw the graph of the movement. Assume that the disk has 100 tracks from 0 to 99.
Calculate the number of disk tracks traversed using the FCFS algorithms for the series of disk track service requests given as 54,36,21,74,46,35,26,67. At the time the first request arrives in the disk request queue, the read/write head is at track 50, moving toward the outer (lower-numbered)tracks. Draw the graph of the movement. Assume that the disk has 100 tracks from 0 to 99.
A single-CPU system has four processes, P1, P2, P3 and P4 in the ready queue. The execution times and I/O needs for these processes are given below. All times are in ms. (hint: when a process starts an IO operation, it is removed from the ready queue and put back at the end of the queue only when it completes its IO). Process P1: Arrives at 0ms, needs 23ms of CPU time. Performs I/O for 5ms after 10ms of its execution time, then another 5ms after 20ms of its execution time. Process P2: Arrives at 3ms, needs 12ms of CPU time. Performs I/O for 10ms after 5ms of its execution time. Process P3: Arrives at 1ms, needs 15ms of CPU time. Performs I/O for 1ms after 7ms of its execution time. Process P4: Arrives at 2ms, needs 8ms of CPU time. Performs I/O for 5ms after 4ms of its execution time. We assume that the CPU is idle if no one of these four processes is using it. Using Round Robin scheduling algorithm with a Time Quantum of 4ms and ignoring the context switch time, determine: a) The…
please no chatgpt answer . Consider a demand-paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference, if the page-table entry is in the associative memory. Assume that 80 percent of the accesses are in the associative memory and that, of those remaining, 10 percent (or 2 percent of the total) cause page faults. What is the effective memory access time? Consider the following page reference string: 1, 2, 3, 4, 2, 1, 5, 6, 2, 1, 2, 3, 7, 6, 3, 2, 1, 2, 3, 6. Assuming demand paging with four frames, Show which pages are resident under the LRU, FIFO, and Optimal replacement algorithms by filling out the following tables. How many page faults would occur…
Consider a disk subjected to I/O requests arriving (following Poisson distribution) at an average rate of requests/second. Assume that on average, there were 5 requests waiting for service in the queue and that each request waits in the queue for about 10 milliseconds, on average. What is the effective arrival rate for this disk?

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