GATE CS I/O Scheduling questions

Consider a $512$ GB hard disk with $32$ storage surfaces. There are $4096$ sectors per track and each sector holds $1024$ bytes of data. The number of cylinders in the hard disk is _________.

Consider a disk with the following specifications: rotation speed of $6000$ RPM, average seek time of $5$ milliseconds, $500$ sectors/track, $512$-byte sectors. A file has content stored in $3000$ sectors located randomly on the disk. Assuming average rotational latency, the total time (in seconds, rounded off to $2$ decimal places) to read the …

Consider the following five disk access requests of the form (request id, cylinder number) that are present in the disk scheduler queue at a given time. $(P, 155), (Q,85), (R,110),(S, 30), (T,115)$ Assume the head is positioned at cylinder $100$. The scheduler follows Shortest Seek Time First scheduling to service the requests. Which one of the following …

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 the form [sector number, cylinder number, platter number] are received by the disk controller at the same time: …

Cylinder a disk queue with requests for $I/O$ to blocks on cylinders $47, 38, 121, 191, 87, 11, 92, 10.$ The C-LOOK scheduling algorithm is used. The head is initially at cylinder number $63$, moving towards larger cylinder numbers on its servicing pass. The cylinders are numbered from $0$ to $199$. The total head movement (in number of cylinders) …

Consider a disk pack with a seek time of $4$ milliseconds and rotational speed of $10000$ rotations per minute (RPM). It has $600$ sectors per track and each sector can store $512$ bytes of data. Consider a file stored in the disk. The file contains $2000$ sectors. Assume that every sector access necessitates a seek, and the average rotational …

Suppose the following disk request sequence (track numbers) for a disk with $100$ tracks is given: $45, 20, 90, 10, 50, 60, 80, 25, 70.$ Assume that the initial position of the R/W head is on track $50$. The additional distance that will be traversed by the R/W head when the Shortest Seek Time First (SSTF) algorithm is used compared to the SCAN …

Consider a typical disk that rotates at $15000$ rotations per minute (RPM) and has a transfer rate of $50 \times 10^6$ bytes/sec. If the average seek time of the disk is twice the average rotational delay and the controller's transfer time is $10$ times the disk transfer time, the average time (in milliseconds) to read or write a $512$-byte sector of …

Suppose a disk has $201$ cylinders, numbered from $0$ to $200$. At some time the disk arm is at cylinder $100$, and there is a queue of disk access requests for cylinders $30, 85, 90, 100, 105, 110, 135$ and $145$. If Shortest-Seek Time First (SSTF) is being used for scheduling the disk access, the request for cylinder $90$ is serviced after …

A file system with $300$ GByte disk uses a file descriptor with $8$ direct block addresses, $1$ indirect block address and $1$ doubly indirect block address. The size of each disk block is $128$ Bytes and the size of each disk block address is $8$ Bytes. The maximum possible file size in this file system is

An application loads $100$ libraries at startup. Loading each library requires exactly one disk access. The seek time of the disk to a random location is given as $10$ ms. Rotational speed of disk is $6000$ rpm. If all $100$ libraries are loaded from random locations on the disk, how long does it take to load all libraries? (The time to transfer data …

A hard disk has $63$ sectors per track, $10$ platters each with $2$ recording surfaces and $1000$ cylinders. The address of a sector is given as a triple $\langle c, h, s \rangle$, where $c$ is the cylinder number, $h$ is the surface number and $s$ is the sector number. Thus, the 0$^{th}$ sector is addresses as $\langle 0, 0, 0 \rangle$, …

A hard disk has $63$ sectors per track, $10$ platters each with $2$ recording surfaces and $1000$ cylinders. The address of a sector is given as a triple $\langle c, h, s \rangle$, where $c$ is the cylinder number, $h$ is the surface number and $s$ is the sector number. Thus, the 0$^{th}$ sector is addresses as $\langle 0, 0, 0 \rangle$, …

Consider a disk system with $100$ cylinders. The requests to access the cylinders occur in following sequence: $4, 34, 10, 7, 19, 73, 2, 15, 6, 20$ Assuming that the head is currently at cylinder $50$, what is the time taken to satisfy all requests if it takes $1\;\text{ms}$ to move from one cylinder to adjacent one and shortest seek time first …

For a magnetic disk with concentric circular tracks, the seek latency is not linearly proportional to the seek distance due to

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 capacity of the disk pack and the number of bits required to specify a particular sector in the disk are respectively:

What is the swap space in the disk used for?

Normally user programs are prevented from handling I/O directly by I/O instructions in them. For CPUs having explicit I/O instructions, such I/O protection is ensured by having the I/O instruction privileged. In a CPU with memory mapped I/O, there is no explicit I/O instruction. Which one of the following is true for a CPU with memory mapped I/O?

Which one of the following is true for a CPU having a single interrupt request line and a single interrupt grant line?

A unix-style I-nodes has $10$ direct pointers and one single, one double and one triple indirect pointers. Disk block size is $1$ Kbyte, disk block address is $32$ bits, and $48$-bit integers are used. What is the maximum possible file size?