Which do you believe?

• Costly FC and SCSI drives are more reliable than cheap SATA drives.
• RAID 5 is safe because the odds of two drives failing in the same RAID set are so low.
• After infant mortality, drives are highly reliable until they reach the end of their useful life.
• Vendor MTBF are a useful yardstick for comparing drives.

According to papers from Google and CMU at FAST ‘07, none of these are backed by empirical evidence. StorageMojo has a good summary of the key points