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OS · Question Set
File System Management interview questions for placements and exams.
Questions
11
Included in this set
Subject
OS
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Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for OS.
In linked allocation, each file is a linked list of disk blocks and the directory holds a pointer to the first block. This method avoids external fragmentation but random access is slow because you must traverse links. It’s one of the basic allocation strategies asked in interviews. :contentReference[oaicite:1]{index=1}
For complete preparation, combine this set with full subject-wise practice for OS. You can also explore other subjects and sets from the links below.
In Linux system directories, /etc is the standard directory where system configuration files are kept. This question tests familiarity with file system structure, which often shows up in interviews. :contentReference[oaicite:3]{index=3}
Free-space management is how a file system tracks which blocks are free for allocation. Two common techniques are a free-list (linked list of free blocks) and a bitmap (array of bits where each bit indicates free or used). The free-list is simple and efficient for sequential allocation but may fragment and traverse slowly for large free lists. A bitmap allows quick access and compact representation, and supports efficient block allocation decisions, but requires scanning and may incur overhead for very large disks. Highlighting trade-offs is important in interview responses.
Journaling file systems record metadata (and sometimes data) changes in a log before applying them. If a crash happens, the system can replay the journal to restore consistency quickly. This technique is widely used in modern file systems like ext4 and XFS. :contentReference[oaicite:4]{index=4}
Extent-based allocation assigns a file one or more large contiguous regions (extents) of disk blocks rather than many small scattered blocks. This reduces fragmentation, improves I/O performance for large sequential reads/writes, and simplifies block mapping. Many modern file systems such as XFS and ext4 use extents for scalability and performance. Demonstrating knowledge of extents can impress interviewers. :contentReference[oaicite:5]{index=5}
In Unix-style systems, to remove files from a directory the user must have write permission (to modify the directory contents) AND execute permission (to access the directory). A directory without execute bit might prevent access. Knowledge of file and directory permissions is a common interview topic.
Mounting is the process by which the operating system makes a file system accessible at a certain directory (the mount point) in the directory tree. The mount point is the directory where the root of the new file system is attached. After mounting, users and programs can access files on that file system by traversing the directory tree. In interviews it’s useful to mention unmounting, mount flags (read-only, noexec) and how mount points tie multiple storage devices into one hierarchical namespace.
The SCAN disk-scheduling algorithm (also called elevator algorithm) moves the disk arm in one direction servicing all pending requests until it hits the end then reverses direction. This reduces seek time by preventing arm starvation and back-and-forth movement. Understanding disk scheduling links file system and device management topics. :contentReference[oaicite:6]{index=6}
A file system is the subsystem of an operating system that manages how data is stored and retrieved on storage media. It handles naming, directories, metadata, allocation and free-space management. Understanding this is key for placement interviews. :contentReference[oaicite:0]{index=0}
An inode is a data structure used in many Unix-style file systems to represent a file or directory. It holds metadata such as the owner, permissions, file size, creation/modification/access times, and pointers to the data blocks where the file’s contents reside. The inode number is an index into an inode table used by the OS. Knowing inodes helps you understand underlying file system implementations. :contentReference[oaicite:2]{index=2}
The fsck (file system check) utility is used to check and repair inconsistencies in file-system metadata after a crash or improper shutdown. It scans file-system structures like inode tables, bitmaps, directory entries and free lists to identify orphaned inodes, dead links, incorrect block counts or mismatches. Then it repairs by clearing or reconnecting entries. Explaining when it runs (boot time, manually) and how it helps restore integrity shows deeper OS knowledge. :contentReference[oaicite:7]{index=7}