Operating Systems Final Part (4) : File Systems & Threads

Map a logical byte to its logical block using floor division by a 512-byte block in contiguous allocation, then locate the physical block from the first block.

Explore the size declaration problem in contiguous file allocation, where predefining exact disk blocks limits file growth and prevents seamless expansion.

Examine the disadvantages of linked list allocation, highlighting non-contiguous blocks causing slow reads and seeks, pointer overhead, and persistent internal fragmentation when file sizes differ from block size.

Explore indexed allocation as an alternative to maintaining a single table by using a per-file index that maps each file block to its disk block, enabling direct random access.

Relate block size and index entry size to index entries per block, and show direct pointers reach one block while indirect pointers yield x, x^2, and x^3 blocks.

Discover free space management with bitmap and linked list to track free disk blocks in RAM, allocate blocks to files, and delete from the free list efficiently.

Explore disk scheduling and why the cpu is faster than io, showing how ordering disk io among multiple processes affects total io time, and compare first-come-first-served with least-io-time strategies.

Explore fcfs disk scheduling with a practical example, showing requests served in their arrival order and calculating 421 cylinder movements and 421 nanoseconds of seek time.

Learn the C-LOOK disk scheduling algorithm, a circular LOOK that combines LOOK and C-SCAN, starting at cylinder 53 and moving in one direction to the outermost request.