COS 3721
ASSIGNMENT 3 SOLUTIONS 2022
, 1 QUESTION 1 A
If a system contains 1000 disk drives, each of which has a 750000 hour MTBF, which of the
following best describes how often a drive failure will occur in that disk farm:
Option 5 - 750,000 drive-hours per failure divided by 1000 drives gives 750
hours per failure—about 31 days or once per month
2 QUESTION 1 A
The manufacturer guarantees a 1-million-hour MTBF for a certain model of disk drive. What
can you conclude about the number of years for which one of these drives is under warranty?
The MTBF tells nothing about the expected lifetime. Hard disk drives are generally designed to have a
lifetime of 5 years. If such a drive truly has a million-hour MTBF , it is very unlikely that the drive will fail
during its expected lifetime.
STUDYWELL NOTES 2
ASSIGNMENT 3 SOLUTIONS 2022
, 1 QUESTION 1 A
If a system contains 1000 disk drives, each of which has a 750000 hour MTBF, which of the
following best describes how often a drive failure will occur in that disk farm:
Option 5 - 750,000 drive-hours per failure divided by 1000 drives gives 750
hours per failure—about 31 days or once per month
2 QUESTION 1 A
The manufacturer guarantees a 1-million-hour MTBF for a certain model of disk drive. What
can you conclude about the number of years for which one of these drives is under warranty?
The MTBF tells nothing about the expected lifetime. Hard disk drives are generally designed to have a
lifetime of 5 years. If such a drive truly has a million-hour MTBF , it is very unlikely that the drive will fail
during its expected lifetime.
STUDYWELL NOTES 2
