A couple useful tidbits of information to help choose disk drives...

[farmerpling2]

These numbers are "rough." Use them to help provide a better understanding of which drives may be the ones that you should buy...

A couple useful pieces of information that you should consider are:

• Warranty - The longer the warranty, the more the drive will cost, but usually it is made of higher quality materials and processes to manufacturer the drive.
  • Consumer <2 years
  • SOHO >3 year
    
  • Enterprise >5 years
• Workload rate (rough data points) - Typically manufacturers use this number to limit the warranty. It provides some information on wear and usage of the drive.
  • Consumer <~180TB transfer/year
  • SOHO <~300TB transfer/year
  • Enterprise >300TB transfer/year
• MTBF -> Statistical measurement used to show you information on failure of disk drives. It gives you a rough idea on a drives possible failure. Generally, the higher the number the less likely you will have a failure.
  • Consumer <750,000 hours
  • SOHO around 1 million hours
    
  • Enterprise >3 million hours
• Nonrecoverable Read Errors per Bits Read -> Think of this as how many bits read before a read failure (i.e. bad block{s}) occur.
  • Consumer - 10E14
  • SOHO - 10E15
    
  • Enterprise - 10E15+ (some as high as 10E16).
• Load / Unload Cycles - How often are the drives armature/heads moved to a safe "park" area. Example: The drive might still be spinning, but if you dropped your laptop, this would decrease the chance of the armature/heads from contacting the rotating media.
  • Consumer - 600,000
  • SOHO - ~1,000,000
    
  • Enterprise - >1,000,000

Using these data points you can make a more educated choice on what disk drives to buy. Everyone can have different reasons why they might choose one choice over another.

I have tried to keep it simple and not expound heavily into technology or math.