if the smart status is ok (green) then you are good, if one or two sectors are red then you are good too, but if smart status goes red then not good, also if hdd makes noises thenget it replaed immediately
There are several "layers" of need for storage:
1) Critical Data - this includes programs, operating system and critical user files (stuff you can't live without). This includes backup drives. This should always be stored on a drive that is reliable.
2) Non-Critical Data - this is data that has been backed up, and if the hard drive dies, you can restore it easily. You can live a "while" without this data. A drive that has had problems can be used - but backups should be run often.
3) Temporary Data - this data is stored on the system, but no need for backup, and if it is lost - who cares. A drive that has problems can be used in this scenario - no backups needed.
Personally - in situation #1 - you should always have a very reliable drive with no known issues. If it dies, you are down.
Situation #2 is if dies, you replace and restore the data. You have a temporary inability to access the data, but you can get it back.
I am amazed at the amount of people who do not backup critical data, and then they scream the loudest when their data is lost. It's never fun, but with backups, anything can be restored....it is just the amount of time you want to spend restoring it.
When you consider the price of a 1TB HD - highly reliable drives are $100 or less. If it takes you 10 hours to buy a replacement drive, install the operating system, and restore your data...your time is worth $10 per hour....I would rather spend my time elsewhere....