IBM introduced first HDD in 1956, storing 5 million characters on 52 disks. Modern HDDs use magnetic platters and heads on moving actuator arms. Data accessed randomly, retaining data when powered off. Most common form factors are 3.5-inch for desktops and 2.5-inch for laptops
Windows Error Checking and chkdsk command are included in Windows. Windows Drive Fitness Test can scan USB drives but not Windows installation drive
Bad sectors are areas on hard drives where data cannot be written. There are two types: physical (damage) and logical (software issues). Physical sectors are irreparable, logical ones are usually repairable
Hard drives rotate at RPM to position magnetic heads for data access. Modern drives typically operate at 5400 or 7200 RPM. Higher RPM generally means faster file access and transmission
Over half of users report external drives not appearing in This PC/My Computer. Issues can occur in Disk Management, Device Manager, or BIOS
Drive may not show up due to connection issues, driver problems, or BIOS settings. Symptoms include Disk Unknown, RAW status, or yellow exclamation marks. Physical damage requires professional repair