File Systems

To keep track of free blocks in a file system, one of the two approaches is generally used - using bitmaps (bit vectors) or using linked lists. Consider that the linked list approach is used to keep track of free blocks...

Consider a hard disk with a rotational speed of 15000 rpm . The time to move the read/ write head from a track to its adjacent track is 1 millisecond. Initially, the head is on track 0 . The number of sectors per track i...

A disk of size 512 M bytes is divided into blocks of 64 K bytes. A file is stored in the disk using linked allocation. In linked allocation, each data block reserves 4 bytes to store the pointer to the next data block. T...

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 d...

Consider two files systems A and B, that use contiguous allocation and linked allocation, respectively. A file of size 100 blocks is already stored in A and also in B. Now, consider inserting a new block in the middle of...

Consider a linear list based implementation in a file system. Each directory is a list of nodes, where each node contains the file name along with the file metadata, such as the list of pointers to the data blocks. Consi...

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 p...

The index node (inode) of a Unix-like file system has 12 direct, one single-indirect and one double-indirect pointers. The disk block size is 4 kB , and the disk block address is 32 -bits long. The maximum possible file...

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 $$6$$ d...

Consider a disk queue with requests for $${\rm I}/O$$ 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 $$63,$$ mov...

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 distanc...

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...

A FAT (file allocation table) based file system is being used and the total overhead of each entry in the FAT is $$4$$ bytes in size. Given a $$100\,\, \times \,\,{10^6}$$ bytes disk on which the file system is stored an...

A file system with 300 G Byte 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 bl...

An application loads $$100$$ libraries at startup. Loading each library requires exactly one disk access. The seek time of the disk to random location is given as $$10$$ $$ms$$. Rotational speed of disk is $$6000$$ $$rpm...

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...

The data blocks of a very large file in the Unix file system are allocated using

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 s...

Consider an operating system capable of loading and executing a single sequential user process at a time. The disk head scheduling algorithm used is First Come First Served $$(FCFS).$$ If $$FCFS$$ is replaced by Shortest...

Using a larger block size in a fixed block size file system leads to

In the index allocation scheme of blocks to a file, the maximum possible size of the file depends on

Consider a disk with the $$100$$ tracks numbered from $$0$$ to $$99$$ rotating at $$3000$$ $$rpm.$$ The number of sectors per track is $$100.$$ the time to move the head between two successive tracks is $$0.2$$ milliseco...

Which of the following disk scheduling strategies is likely to give the best throughput?

RAID configurations of disks are used to provide

Formatting of floppy disk refers to

A file system with a one-level directory structure is implemented on a disk with disk block size of $$4$$ K bytes. The disk is used as follows: Disk-block $$0:$$ File Allocation Table, consisting of one $$8$$-bit entry p...

The head of a moving head disk with $$100$$ tracks numbered $$0$$ to $$99$$ is currently serving a request at tract $$55.$$ If the queue of requests kept in $$FIFO$$ order is $$10, 70, 75, 23, 65$$ Which of the two disk...

If the overhead for formatting a disk is $$96$$ bytes for $$40000$$ bytes sector, Compute the unformatted capacity of the disk of the following parameters: Number of surface: $$8$$ Outer diameter of the disk : $$12cm$$ I...

If the disk in (a) is rotating at $$3600$$ rpm, determine the effective data transfer rate which is defined as the number of bytes transferred per second between disk and memory.

A certain moving arm disk storage, with one head, has the following specifications. Number of track/recording Surface $$=200$$ Disk rotation speed $$=2400$$$$rpm$$ Track storage capacity $$=62,500$$ $$bits$$ The average...

The root directory of a disk should be placed:

A certain moving arm disk-storage device has the following specifications: Number of tracks per surface $$=4004$$ Track storage capacity $$=130030$$ bytes Disk speed $$=3600$$ rpm Average seek time $$=30$$ m secs. Estima...

Assuming the current disk cylinder to be $$50$$ and the sequence for the cylinders to be $$1, 36, 49, 65, 53, 1, 2, 3, 20, 55, 16, 65$$ and $$78$$ find the sequences of servicing using (i) shortest-seek time first $$(SST...

Disk requests come to disk driver for cylinders $$10,22,20,2,40,56$$ and $$38,$$ in that order at a time when the disk drive is reading from cylinder $$20.$$ The seek time is $$6msec$$ per cylinder. Compute the total see...