Data Recovery

In 2018, a second-hand study from a university in the United Kingdom made headlines after researchers purchased 200 used hard drives from eBay and other online marketplaces. Out of 200 drives, they found that 59% still contained recoverable data—including personal photographs, financial records, and in one case, a complete database of a company’s payroll system. The previous owners had formatted these drives. Some had even run “secure erase” tools. Yet the data remained. ...

In 1987, three researchers at the University of California, Berkeley published a paper that would fundamentally change how we think about data storage. David Patterson, Garth Gibson, and Randy Katz proposed something counterintuitive: instead of buying one expensive, reliable disk drive, why not combine many cheap, unreliable ones into a system more reliable than any single drive could ever be? They called it RAID—Redundant Arrays of Inexpensive Disks. The insight was mathematical, not magical. By distributing data across multiple drives with carefully calculated redundancy, you could achieve both performance and reliability that would be impossible with a single disk. The key was a simple operation that most programmers learn in their first computer science course: XOR. ...