A Redundant Array of Independent (or Inexpensive) Disks (RAID) often requires a separate controller card for management. The primary purpose of a RAID is to combine several physical devices into a single logical unit for the sake of redundancy and performance.
This is especially relevant to our interests. Carnegie Mellon University published a study in 2007 on hard drive failure rates. They found that hard drives fail at a rate of about 3% per year. Furthermore, they found that drive type and interface contributed little to disk longevity, and that hard drives do not reflect a tendency to fail early as was commonly accepted. These findings were largely corroborated by a parallel study released the same year by Google.
What does this mean? For our purposes in building a highly available server, it means hard drives should be looked at with great disdain. Larger...
