Disk Management
Disk management ensures efficient storage, retrieval, and maintenance of data, optimizing performance and reliability.
Disk Structure & Organization
A disk consists of plates divided into tracks and sectors, where data is stored magnetically. The OS manages these storage units through file systems like NTFS, FAT32, and ext4.
🔹 Example: Your laptop’s SSD or HDD organizes files using partitions, ensuring smooth access.
Disk Scheduling Algorithms
Since multiple processes request disk access, scheduling algorithms optimize read/write efficiency:
1️⃣ FCFS (First-Come, First-Served) – Simple but may cause slow access times.
2️⃣ SSTF (Shortest Seek Time First) – Prioritizes nearest disk requests.
3️⃣ SCAN & C-SCAN – Works like an elevator, scanning disks in one direction for fairness.
4️⃣ LOOK & C-LOOK – Optimized versions that reduce unnecessary movement.
🔹 Example: A database server uses SSTF or SCAN to process disk queries efficiently.
Disk Space Allocation Methods
1️⃣ Contiguous Allocation – Allocates consecutive blocks, causing fragmentation over time.
2️⃣ Linked Allocation – Uses pointers to manage files dynamically.
3️⃣ Indexed Allocation – Stores file locations in an index for fast retrieval.
🔹 Example: SSDs use indexed allocation for fast data access, while traditional HDDs may rely on linked allocation for flexibility.
RAID & Fault Tolerance
RAID (Redundant Array of Independent Disks) ensures data protection and performance:
🔹 RAID 0: Improves speed via striping but lacks redundancy.
🔹 RAID 1: Mirrors data for backup.
🔹 RAID 5/6: Combines striping and parity for fault tolerance.
🔹 Example: Servers use RAID 1 or RAID 5 to prevent data loss in case of disk failures.
Conclusion
Disk management is critical for system efficiency, balancing speed, data integrity, and reliability. Optimizing disk scheduling, space allocation, and RAID strategies ensures smooth data access and storage performance across various applications.