Recent questions tagged disks

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Galvin Edition 9 Exercise 10 Question 23 (Page No. 501)
Discuss the reasons why the operating system might require accurate information on how blocks are stored on a disk. How could the operating system improve file-system performance with this knowledge ?

asked Mar 22 in Operating System by akash.dinkar12 Boss (40.6k points) | 34 views

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Galvin Edition 9 Exercise 10 Question 7 (Page No. 497-498)
It is sometimes said that tape is a sequential-access medium, whereas a magnetic disk is a random-access medium. In fact, the suitability of a storage device for random access depends on the transfer size. The term streaming transfer rate ... and tape. $f$. When is a tape a random-access device, and when is it a sequential-access device ?

asked Mar 22 in Operating System by akash.dinkar12 Boss (40.6k points) | 28 views

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Ace Test Series: Operating System - Disks
Consider a disk with an average seek time of $4$ ms. Motor speed 15000RPM 512B sector 500 sector per track A file occupies all of the sectors on $5$ tracks Each track reading requires average seek time and average rotational delay What will be transfer time of $1$ track?

asked Mar 7 in Operating System by srestha Veteran (114k points) | 66 views

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Testbook Test Series: Operating System - Disks
A UNIX style i-node has 15 direct pointers and one single, one double and one triple indirect pointers. The disk block size is 1KB, disk block address is 64 bits and 48 bit integers are used. What is the maximum possible fize size in bytes? Thanks!

asked Jan 28 in Operating System by Abhipsa Mishra (159 points) | 65 views

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Ace Test Series: CO & Architecture - Secondary Memory

asked Jan 28 in CO & Architecture by chirudeepnamini (7 points) | 53 views

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Question from Gradeup mock test 10 Q.44
Find how much disk space (in surfaces) will be required to store 300,000 120-byte logical records, if the disk is fixed sector with 512 bytes/sector, with 96 sectors/track, 110 tracks per surface, and 8 usable surfaces. Ignore any file ... tracks = 790 track = 790/110 = 8 surfaces. How come number of records is 303150 rather than 300000? Please explain.

asked Jan 27 in Operating System by Aman Janko (57 points) | 34 views

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2 answers

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Ace Test Series 2019: CO & Architecture - Hard Disk

asked Jan 13 in CO & Architecture by Shankar Kakde (373 points) | 46 views

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Disk Total access time
Consider a typical disk that transfers at a rate of 30 MBps and rotates at 5000 RPM. The average seek time of disk is twice average rotation delay and assume no controllers transfer time then, what is average time(in ms) to read or write 1 MB of data ? 48 ms 45 ms 55 ms 51 ms

asked Jan 12 in Operating System by Na462 Loyal (8.7k points) | 94 views

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MadeEasy Test Series: Operating System - Disks
Consider a unix inode which maintains $5$ direct disk blocks, $1$ single indirect, $1$ double indirect and $1$ triple indirect DBA. Disk block size is $4 \text{ KB }$ and disk block address is $32 \text{ bits }$. Which of the following is maximum possible file ... $256 \text{ GB }$ $512 \text{ GB }$ $2 \text{ TB }$ Answer by ME: Option $(A)$

asked Dec 26, 2018 in Operating System by zeeshanmohnavi Junior (857 points) | 126 views

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Ace Test Series: CO & Architecture - Disk
In the solution to this question it is given that the number of rotations needed is 2.75. How we got 2.75?

asked Nov 19, 2018 in CO & Architecture by VJ2793 (41 points) | 84 views

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#OS #COA Disks question regarding bits to find a particular track?
Consider a disk pack with 16 surfaces, 128 tracks per surface and 256 sectors per track. 512 bytes of data are stored in a bit serial manner in a sector. The number of bits required to specify a particular track in the disk are ?

asked Oct 9, 2018 in Operating System by iarnav Loyal (9.8k points) | 65 views

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#COA User Gate 2013 Disk Question Doubt
Source of question - https://gateoverflow.in/1540/gate2013-29 Consider a hard disk with 16 recording surfaces (0−15) having 16384 cylinders (0−16383) and each cylinder contains 64 sectors (0−63). Data storage capacity in each sector ... , but couldn't get the reverse engineering thing given in best answer. Someone please simplify and explain this question

asked Oct 8, 2018 in CO & Architecture by iarnav Loyal (9.8k points) | 41 views

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#OS Capacity of formatted DISK
If the overhead for formatting a disk is 96 bytes for a 4000 byte sector, Compute the formatted capacity of the disk for the following parameters: Number of surfaces: 8 Outer diameter of the disk: 12 cm Inner diameter of the disk: 4 cm Inner track ... as (recording width)/(inner track space) And since 96 bytes are wasted from 4000 Bytes thus we left w/ 3904 B/sector

asked Oct 2, 2018 in Operating System by iarnav Loyal (9.8k points) | 67 views

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#OS User Gate Disk Question
A certain moving arm disk-storage device has the following specifications: Number of tracks per surface=404 Track storage capacity=130030 bytes. Disk speed=3600 rpm Average seek time=30 m secs. Find the disk storage capacity and the data transfer rate. =============== How we can find disk capacity without having sectors and also how to find data transfer rate?

asked Oct 2, 2018 in Operating System by iarnav Loyal (9.8k points) | 105 views

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Test Series

asked Sep 9, 2018 in CO & Architecture by ben10 (465 points) | 39 views

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16

Magnetic Disk
Ans. 52 msec

asked Aug 4, 2018 in Operating System by Na462 Loyal (8.7k points) | 64 views

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17

DMA Transfer rate
Consider 8-bit DMA device operating in cycle stealing mode (Single Transfer Mode). Each DMA cycle takes 6 clock and each clock is of 2 MHz. An intermediate CPU machine cycle take 2 μsec. What is the data transfer rate of DMA? Ans. 200 KB/sec

asked Jul 23, 2018 in CO & Architecture by Na462 Loyal (8.7k points) | 189 views

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MadeEasy Test Series: Operating System - Disk Scheduling
Suppose a disk has 200 cylinders numbered from 0 to 199. At some time, disk arm is at cylinder 76 and there is a queue of disk access requests for cylinders: 54, 32, 108, 22, 67, 77, 87, 87, 42, 82 The ... R/W head when the SCAN (elevator) algorithm used is ________tracks. Assume that SCAN algorithm moves towards 199 when it starts execution.

asked Jul 18, 2018 in Operating System by Na462 Loyal (8.7k points) | 209 views

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19

Disk Accessing
I solved this question correctly. I have a slight doubt though if say in question it says that Disk address is of K bits then what it represents 2^k Sectors or 2^k blocks ???

asked Jul 12, 2018 in Operating System by Na462 Loyal (8.7k points) | 70 views

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20

Difference between cylinder and tracks
I am getting confused with these two terms cylinder and tracks a) Is it cylinder = tracks ? b) How does addressing works in terms of surface and cylinder , track and sector https://gateoverflow.in/1337/gate2009-51

asked Jun 13, 2018 in Operating System by ejaz (233 points) | 35 views

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21

Operating System
In a computer system, three files of size 11052 B, 4992 B and 5172 B need to be stored. For storing these files on disk, we can use either 100 B disk block or 200 B disk block. For each block used to store a file, 2 bytes of book ... data from a file, but not both. What is the total space required for storing the files using 100 B and 200 B disk blocks respectively___________

asked Jun 9, 2018 in Operating System by srestha Veteran (114k points) | 38 views

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22

Data Transfer
I have a normal Doubt Consider a Scenario:- 1. Total number of block are = K Total number of records per block = P Size of record = B bytes And we need to transfer all the blocks in memory. Avg rotation latency = R Seek time = S Block transfer rate ... rotation latency and transfer time for every block rt? else in one access i can transfer everything??? Plz correct me if i am wrong?

asked Mar 20, 2018 in Operating System by Na462 Loyal (8.7k points) | 47 views

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23

GATE2018-53
Consider a storage disk with $4$ platters (numbered as $0, 1, 2$ and $3$), $200$ cylinders (numbered as $0, 1, , 199$), and $256$ sectors per track (numbered as $0, 1, 255$). The following $6$ disk requests of ... is negligible. The total power consumption in milliwatts to satisfy all of the above disk requests using the Shortest Seek Time First disk scheduling algorithm is _____

asked Feb 14, 2018 in Operating System by gatecse Boss (18.2k points) | 3.9k views

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24

Ace Test Series: Operating System - Magnetic Tape Memory
How to solve this type??

asked Jan 21, 2018 in Operating System by Deepak Mokili (307 points) | 67 views

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number of disk block accesses required
Suppose a file F of size 8KB is shared by 50 processes, each process read the entire F 5 times sequentially, disk uses linked allocation policy to store both Inode and data of the file with block size 256 byte in FAT and Block Pointer takes 2 bytes. The number of disk block access related to access the file F in executing all the 50 processes is

asked Jan 21, 2018 in CO & Architecture by MIRIYALA JEEVAN KUMA Active (2.5k points) | 68 views

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#Ace Test Series #Disk Transfer Rate
A disk unit has 20 recording surfaces. It has a total of 14,000 cylinders. There is an average of 400 sectors per track and each sector contains 512 bytes of data.Find the storage capacity of the disk unit. If disk rotates at a speed of ... by 20 or not ?There is nothing mentioned in the question about read/write heads so how to solve these type of questions?

asked Jan 15, 2018 in CO & Architecture by Deepak Mokili (307 points) | 66 views

+2 votes

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27

self doubt
Is this formula ALWAYS correct? Average Disk Latency (in milliseconds) = 30000/RPM

asked Jan 14, 2018 in Operating System by Balaji Jegan Loyal (5.4k points) | 46 views

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28

Disks
Consider the following requests to disk: 138,144,133,95,195,70,20,223,124 Assume the head is initially at 136 and algorithm used is SSTF then the number of times head has changed its direction excluding initial movement is _____________

asked Jan 7, 2018 in Operating System by Tuhin Dutta Loyal (9.6k points) | 48 views

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1 answer

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MadeEasy Test Series: Operating System - Disks
A disk rotates at a speed of 3600 rpm. It has 4000 cylinders, 16 surface and 206 sectors per tracks. Track storage capacity is 2048 bytes. What is the average latency time (in msec) and data transfer rate (in kbps) respectively. A 16.66, 12.28 B 8.33, 196.48 C 16.66, 196.48 D 8.33, 12.28 Given answer is d, but i got 8.33 , 960Kbps

asked Dec 18, 2017 in Operating System by rahul sharma 5 Boss (27.2k points) | 195 views

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MadeEasy Test Series: Operating System - Disks
Consider linked allocation system, a program has just read the 15th disk block. After some point of time, If it next want to use the 20th block, then how many disk blocks must the program access? a: 5 b: 10 c:15 d:20

asked Dec 18, 2017 in Operating System by rahul sharma 5 Boss (27.2k points) | 160 views

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