Assume that disks with lower failure rates are more expensive. Specifically, disks are available at a higher cost that will start doubling their failure rate in year 8 rather than year 5. How much more would you pay for disks if your intent is to keep them for 7 years? What about 10 years?

Measurements and statistics provided by storage vendors must be carefully interpreted to gain meaningful predictions about their system behavior. The following table provides data for various disk drives.

a. b. # of Drives 1000 1250 Hours/Drive 10,512 8760 Hours/Failure 1,200,000 1,200,000