Having examined process scheduling, synchronization, and volatile memory virtualization, we confront the challenge of persistence. We analyze how the kernel virtualizes non-volatile physical storage blocks into structured, named byte streams: File Abstractions, Directory Trees, Inode Allocation Schemes, and Crash Consistency via Journaling.
fork() and dup().fsck).Analyze how the operating system abstracts physical storage blocks into named, linear byte streams. Study file metadata (stat/inode), access modes, and the kernel's 3-tier descriptor architecture.
Investigate directory file layouts, linear and hashed directory entries, hierarchical pathname resolution from root, and the critical mechanical differences between hard links and symbolic links.
Dissect on-disk physical layouts: contiguous allocation, chained lists, File Allocation Tables (FAT), and UNIX Inodes with direct, indirect, double-indirect, and triple-indirect block pointers.
Examine buffer cache architectures, read-ahead caching, disk defragmentation, crash consistency protocols, Write-Ahead Logging (WAL), and journaling filesystems (ext4, NTFS, ZFS).
Trace file descriptor indirection across fork(), dup2(), and independent open() calls.
Step through recursive path resolution, inode lookups, and hard link link-count mechanics.
Calculate file offsets and navigate direct, indirect, and double-indirect block arrays.
Simulate power loss mid-transaction to observe Write-Ahead Logging crash recovery.