What are some file system benchmarking tools?

Common tools for measuring file system performance include:

• fio: Flexible I/O tester.
• dd: Simple disk I/O benchmarking.
• bonnie++: Comprehensive file system and storage testing tool.
• ioping: Disk latency testing tool.

How do file systems handle metadata updates?

Usually, file systems employ write-ahead logging or journaling to guarantee that metadata updates are applied securely. In the case that the system crashes during an update, this avoids corruption.

What is the difference between extents and traditional block allocation?

• Extents: Allocate contiguous blocks for a file, reducing fragmentation.
• Traditional Block Allocation: Allocates blocks individually, leading to potential fragmentation.

What is a distributed lock manager (DLM) in file systems?

A DLM coordinates access to shared files in distributed systems, preventing conflicts and ensuring consistency in multi-user environments.

What is the role of the Master Boot Record (MBR) in file systems?

The Master Boot Record (MBR) is located at the first sector of a storage device. It contains:

• Partition table.
• Bootloader for the operating system. The MBR helps locate and initialize the file systems within the defined partitions.

What are the common file attributes stored by file systems?

File systems store attributes such as:

• Name: The name of the file.
• Type: File type (e.g., text, binary).
• Size: File size in bytes.
• Location: Physical location on the storage device.
• Permissions: Read, write, execute settings.
• Timestamps: Creation, modification, and last access times.

How are directories implemented in file systems?

Directories are implemented using various data structures, such as:

• Linear List: Simplest implementation, stores file names and pointers sequentially.
• Hash Table: Allows fast lookup of file names.
• B-Tree: Provides a balanced, hierarchical structure for efficient search, insert, and delete operations.

What are volume management techniques in file systems?

Volume management involves organizing and managing storage devices and partitions. Techniques include:

• Logical Volume Management (LVM): Provides flexible partitioning and resizing.
• RAID: Combines multiple physical disks into a single logical unit.
• Partitioning Tools: Tools like fdisk, parted and Disk Management.

What is a file control block (FCB)?

A File Control Block is a data structure used by the OS to store information about an open file. It contains:

• File attributes (name, size, type).
• Access control information.
• File location pointers.

What is block allocation, and what are its types?

Block allocation is the process of assigning disk blocks to files. Types include:

• Contiguous Allocation: Assigns consecutive blocks.
• Linked Allocation: Uses pointers to link blocks.
• Indexed Allocation: Uses an index block to store pointers to data blocks.

What are the advantages of ext4 over ext3?

Ext4 provides several enhancements:

• Larger File Size and Volume Support: Supports volumes up to 1 exabyte and files up to 16 terabytes.
• Extents: Reduces fragmentation by allocating contiguous blocks.
• Faster File System Checking: Includes a mechanism to track unallocated blocks for faster consistency checks.

How does a file system handle concurrency?

Concurrency is managed using:

• Locks: Prevent multiple processes from modifying the same file simultaneously.
• Semaphores: Coordinate access to shared resources.
• File Open Modes: Specify whether a file is opened for exclusive or shared access.