I bought a Prestige 500 GB External Hard Drive last month and took all my music off my computer and put it on the hard drive. My question is, am i better off leaving it on my computer also in case anything happens to it, and also whats an average lifespan of an external hard drive. Last question is should i turn it off when not in use?
Yes, turn it off when not in use. I would burn as much media as you could to a disk (compress it first). Failing that I would keep as much as you could on your original drive. That's what an external is for; backups. not for the sole copy. maybe JMO though I don't know how long they last but I do know keeping it turned off will extend its lifespan and also keep it from being able to be cracked into by anyone you don't want on it (unplug it entirely, actually).
I have been through three eternal hard drives.They do fail and yes the first time it happened I made the mistake of not burning those files The external hard drives are a convenient temporary place to store files but you should always burn them first. BTW There is also a virus that infects external hard drives that are extremely difficult to detect and clean.Many scanners will not detect them
I know it is a little expensive but I always buy two hard drives and just mirror the data on each. One I use as a slave internally and one I place in a hard enclosure externally. A backup of the backup if you will. I hate buying externals built to go because they seem to fail more often than not. At least when you have an enclosure, you can find another HDD to place back in it for a fraction of the cost that you would spend on a pre-built one.