File Systems - Practice MCQs for CCAT

Correct Answer: C - Linked allocation

FAT uses linked allocation with a table storing links.

Correct Answer: D - File metadata (permissions, pointers)

Inode stores file metadata: permissions, size, pointers to data blocks.

Correct Answer: A - Special file containing file entries

Directory is a special file that contains entries for files and subdirectories.

Correct Answer: D - Bit vector/Linked list

Free space tracked using bit vector, linked list, or grouping.

Correct Answer: A - External fragmentation

Contiguous allocation suffers from external fragmentation.

Correct Answer: B - Index block with pointers

Indexed allocation uses an index block containing pointers to data blocks.

Correct Answer: B - Elevator algorithm

SCAN moves like an elevator from one end to another.

Correct Answer: D - Shortest Seek Time First

SSTF services request closest to current head position.

Correct Answer: C - Hard link shares inode, soft link is pointer

Hard link shares inode (same file). Soft link is pointer to file path.

Correct Answer: B - Logs changes for crash recovery

Journaling logs transactions to recover from crashes.

Correct Answer: B - Sequential, Direct, and Indexed

Files can be accessed sequentially, directly (random), or through indexed methods.

Correct Answer: C - Redundant Array of Independent Disks

RAID combines multiple disks for redundancy and/or performance improvement.

Correct Answer: C - Striping without redundancy

RAID 0 stripes data across disks for performance but provides no redundancy.

Correct Answer: C - Mirroring for redundancy

RAID 1 mirrors data across disks for redundancy.

Correct Answer: B - Code to boot the operating system

Boot block contains the code needed to start and load the operating system.

Correct Answer: A - Scans in one direction only, jumps back

C-LOOK services requests in one direction, then jumps to start without servicing.

Correct Answer: C - Time to move head to correct track

Seek time is the time taken to move the disk head to the correct track.

Correct Answer: B - Time for disk sector to rotate under head

Rotational latency is the time for the desired sector to rotate under the head.

Correct Answer: D - Bit vector or linked list

Free blocks are tracked using bit vectors, linked lists, or grouping methods.

Correct Answer: B - File system metadata (size, block count, etc.)

Superblock contains file system metadata like size, number of blocks, and inodes.

Correct Answer: B - Linked allocation

Linked allocation stores each file as a linked list of disk blocks scattered anywhere on the disk. Each block contains a pointer to the next block. It eliminates external fragmentation but doesn't support direct access.

Correct Answer: D - Simple and supports both sequential and direct access efficiently

Contiguous allocation stores files in consecutive disk blocks, allowing simple implementation and efficient sequential and direct access. However, it suffers from external fragmentation and difficulty in file growth.

Correct Answer: D - A data structure that stores metadata about a file (size, permissions, pointers to data blocks)

An inode (index node) is a data structure in Unix/Linux file systems that stores metadata about a file: file size, ownership, permissions, timestamps, and pointers to the data blocks. It does not store the filename.

Correct Answer: D - SSTF (Shortest Seek Time First)

SSTF (Shortest Seek Time First) selects the I/O request closest to the current position of the disk head, minimizing seek time for each individual request. However, it may cause starvation for distant requests.

Correct Answer: A - The disk arm moves in one direction servicing requests, then reverses direction

SCAN (elevator algorithm) moves the disk arm in one direction, servicing all requests along the way until it reaches the end of the disk, then reverses direction and services requests on the return trip.

Correct Answer: A - Each file has an index block containing pointers to all its data blocks

Indexed allocation assigns an index block to each file. The index block contains pointers to all the data blocks of the file. This supports direct access without external fragmentation.

Correct Answer: C - A special type of file that contains information about other files

A directory is a special file that contains a list of entries mapping file names to their metadata (such as inode numbers in Unix). It provides a way to organize and locate files in the file system.

Correct Answer: C - A hard link points to the inode; a soft link points to the file path

A hard link is a direct reference to the inode of a file — both names share the same inode. A soft (symbolic) link is a separate file that contains the path to the target file. Hard links can't cross file systems; soft links can.

Correct Answer: D - A file system that uses a table to track which clusters belong to which files

FAT (File Allocation Table) is a file system that maintains a table mapping each cluster on the disk. Each entry in the table indicates the next cluster of a file or marks a cluster as free, end-of-file, or bad.

Correct Answer: D - The disk arm moves in one direction servicing requests, then returns to the beginning without servicing requests

C-SCAN (Circular SCAN) moves the disk arm in one direction servicing requests. When it reaches the end, it returns to the beginning of the disk without servicing requests, then starts again. It provides more uniform wait times.

Correct Answer: B - A data structure containing information about a file (permissions, size, location)

A File Control Block (FCB) is a data structure maintained by the OS for each file. It contains file attributes such as name, type, size, location, permissions, and dates. In Unix, the inode serves as the FCB.

Correct Answer: A - To store metadata about the file system itself (size, block count, free blocks, inode count)

The superblock contains critical metadata about the file system: total size, block size, total and free block counts, total and free inode counts, and the location of the inode table. Corruption of the superblock can destroy the file system.

Correct Answer: B - Tree-structured directory

A tree-structured directory organizes files in a hierarchical tree where each directory can contain files and subdirectories. Most modern file systems use this structure (e.g., /home/user/documents).

Correct Answer: C - Recording changes in a log before applying them to the file system for crash recovery

Journaling records intended file system changes in a log (journal) before applying them. If the system crashes during an operation, the journal can be used to recover the file system to a consistent state.

Correct Answer: B - 640

FCFS processes requests in order: |53-98| + |98-183| + |183-37| + |37-122| + |122-14| + |14-124| + |124-65| + |65-67| = 45 + 85 + 146 + 85 + 108 + 110 + 59 + 2 = 640 cylinders.

Correct Answer: A - Like SCAN but the arm reverses when there are no more requests in that direction

LOOK is similar to SCAN, but instead of going all the way to the end of the disk, the arm reverses direction when there are no more requests in the current direction. This reduces unnecessary head movement.

Correct Answer: C - No support for direct (random) access and overhead of pointers

Linked allocation does not support direct (random) access efficiently because accessing the nth block requires traversing all previous blocks. Also, space is wasted in each block for storing the pointer to the next block.

Correct Answer: C - To rearrange fragmented data so that files are stored in contiguous blocks

Disk defragmentation rearranges the data on a disk so that files are stored in contiguous blocks, improving read/write performance by reducing seek time. It is mainly beneficial for HDDs, not SSDs.

Correct Answer: D - A directory where a file system is attached to the directory tree

A mount point is a directory in the existing file system where a new file system (from a partition, disk, or network share) is attached and made accessible. For example, /mnt/usb is a common mount point.

Correct Answer: D - Combining multiple disks for improved performance, reliability, or both

RAID combines multiple physical disks into a logical unit to improve performance (through striping), reliability (through mirroring/parity), or both. Common levels include RAID 0, 1, 5, 6, and 10.

Correct Answer: B - RAID 0 stripes data across disks (no redundancy); RAID 1 mirrors data (full redundancy)

RAID 0 stripes data across multiple disks for better performance but provides no redundancy (one disk failure loses all data). RAID 1 mirrors data across disks for full redundancy (can survive one disk failure).

Correct Answer: A - To specify detailed permissions for each user or group on a file or directory

ACLs provide fine-grained access control by specifying permissions for individual users or groups on each file or directory, going beyond the traditional owner/group/others permission model.

Correct Answer: A - Owner: read/write/execute, Group: read/execute, Others: read only

rwxr-xr-- means: Owner has read, write, and execute (rwx); Group has read and execute (r-x); Others have read only (r--). In octal, this is 754.

Correct Answer: A - The fourth extended file system, commonly used in Linux with features like journaling and large file support

ext4 (Fourth Extended File System) is a widely used Linux file system that supports journaling, large file sizes (up to 16 TB), large volumes (up to 1 EB), extents-based allocation, and backward compatibility with ext3/ext2.

Correct Answer: A - The smallest unit of data that can be read from or written to a disk by the file system

A block (or cluster in FAT) is the smallest unit of disk space that the file system allocates. Common block sizes are 1 KB, 2 KB, or 4 KB. Even if a file is smaller than a block, one full block is allocated.

Correct Answer: A - To open a file and return a file descriptor for subsequent read/write operations

The open() system call opens a file and returns a file descriptor — a small integer used by the process to refer to the file in subsequent read(), write(), and close() operations.

Correct Answer: D - New Technology File System, the primary file system for Windows with features like journaling, ACLs, and encryption

NTFS (New Technology File System) is the primary file system for Windows. It supports journaling, access control lists (ACLs), file compression, encryption (EFS), disk quotas, and large file sizes.

Correct Answer: B - Sequential access reads data in order; direct access can read any block without reading preceding blocks

Sequential access reads data in order from beginning to end (like a tape). Direct (random) access can read or write any block directly by specifying its position, without accessing preceding blocks (like a disk).

Correct Answer: C - An abstraction layer that provides a common interface for different file system implementations

VFS (Virtual File System) is an abstraction layer in the OS that provides a uniform interface for different file system types (ext4, NTFS, FAT, etc.). Applications use the same system calls regardless of the underlying file system.

Correct Answer: A - Tracking which disk blocks are available for allocation using techniques like bit vectors or linked lists

Free space management tracks available disk blocks. Common methods include bit vector (bitmap) where each bit represents a block (0=free, 1=allocated), and linked lists where free blocks are linked together.