What is a reasonable age at which to replace a working computer hard drive (Western Digital)? This is not a mission-critical drive, and though I make backups several times per year it would be a pain if the drive fails. The drive in question is 10 years old and is approaching 50000 hours of use. I'm thinking new drives are so cheap that delaying replacement may be more unwise than frugal. OTOH maybe these drives are built for 20+ years and 100000+ hours of use. What's a reasonable time period to go before replacement?