Free space management in Operating Systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is free space management in operating systems?

Free space management is the method used by an operating system to keep track of unused disk space so that it can allocate space efficiently for new files.

beginner

Name two common methods of free space management.

Two common methods are the free list method and the bitmap method.

intermediate

How does the free list method work?

The free list method keeps a linked list of all free disk blocks. When space is needed, blocks are taken from this list and returned when freed.

intermediate

What is a bitmap in free space management?

A bitmap is a sequence of bits where each bit represents a disk block; 0 means free and 1 means used. It helps quickly find free blocks.

beginner

Why is efficient free space management important?

Efficient free space management helps reduce wasted disk space, speeds up file allocation, and improves overall system performance.

Which of the following is NOT a method of free space management?

A Bitmap

B Contiguous allocation

C File allocation table

D Free list

Contiguous allocation is a file allocation method, not a free space management method.

In a bitmap for free space management, what does a bit value of 0 represent?

A Used block

B Reserved block

C Corrupted block

D Free block

In a bitmap, 0 indicates the block is free and available for use.

What data structure is commonly used in the free list method?

A Array

B Stack

C Linked list

D Queue

The free list method uses a linked list to keep track of free disk blocks.

Why might a bitmap be preferred over a free list?

A It allows faster searching for free blocks

B It uses less memory

C It is easier to implement

D It stores file data

Bitmaps allow quick scanning to find free blocks, making allocation faster.

What happens when a file is deleted in terms of free space management?

A Its blocks are added back to free space

B Its blocks are marked as used

C The file is moved to another disk

D The file is compressed

When a file is deleted, its disk blocks are marked free so they can be reused.

Explain the free list and bitmap methods of free space management and their differences.

Think about how each method tracks free blocks and how easy it is to find free space.

Why is managing free space important for an operating system's performance?

Consider what happens if free space is not tracked well.