How does the operating system handle file access?

The operating system handles file access in the following steps:

1. File open: The OS verifies permissions and creates a file descriptor or handle.
2. Read/Write: The OS translates file operations into disk operations via the file system.
3. File close: Resources associated with the file descriptor are released.

What are the advantages of a hierarchical file system?

• Organized Structure: Files are stored in directories, which can be nested for better organization.
• Scalability: Easier to manage a large number of files.
• Efficient Access: Pathnames provide a straightforward way to locate files.

What is fragmentation in a file system?

Fragmentation occurs when files are stored in non-contiguous blocks on the disk, leading to slower read/write performance.

• Types of Fragmentation:
  • Internal Fragmentation: Unused space within allocated blocks.
  • External Fragmentation: Non-contiguous free space on the disk.

What is the difference between synchronous and asynchronous file I/O?

• Synchronous I/O: The application waits for the file operation to complete before continuing execution.
• Asynchronous I/O: The application continues execution while the file operation is processed in the background.

How do file permissions work in Unix-like systems?

Unix file permissions are based on three categories:

1. Owner
2. Group
3. Others

Each category has three types of permissions:

• Read (r): Permission to read the file.
• Write (w): Permission to modify the file.
• Execute (x): Permission to execute the file.

Permissions are displayed as a string, e.g., -rwxr–xr–.

What is Copy-on-Write (CoW) in file systems?

Copy-onWrite is a method in which data copies are not produced instantly. Rather, they are only produced when changes are performed. ZFS and Btrfs employ this to enhance data integrity and optimize storage.

What are symbolic links? How do they differ from shortcuts?

Pointers to a file or directory’s position within the file system are known as symbolic links. They function seamlessly with file operations and are managed by the file system, in contrast to shortcuts.

How does caching improve file system performance?

Caching stores frequently accessed data in memory, reducing the need for repeated disk access. It can occur at various levels:

• Disk cache: Managed by the hardware.
• Page cache: Managed by the OS.
• Application cache: Managed by software.

What is a file descriptor?

A file descriptor is an integer assigned by the OS to identify an open file or resource. Applications use file descriptors to perform operations like reading, writing, or closing files.

What is Access Control List (ACL)?

A file or directory’s ACL is a list that indicates which users or groups have particular permissions (read, write, execute).

What are the components of a file system?

Key components of a file system include:

• Boot Block: Contains boot information.
• Superblock: Stores metadata about the file system.
• Inode Table: Holds inodes for files.
• Data Blocks: Store the actual file data.
• Directory Structure: Organizes files into directories

How do file systems handle large files?

File systems handle large files using techniques like:

• Indexed allocation: A single index block stores pointers to data blocks.
• Multi-level indexing: Combines direct, indirect, and double indirect pointers.
• Extent-based allocation: Groups contiguous blocks into extents for efficient allocation.