Sure you can still access the data if one of your drives fails, so that can be a really good argument for RAID.If you are using a raid 1, 5, 6 and etc, you can still access data if a drive fails. I'm mostly on Raid 6 + hot spare arrays now so in theory it rebuilds using the drive just sitting there... It does cost more, but losing multiple TB's of data is crazy. I agree with the backup comment. Backups are always good, but I'm lazy and only schedule daily backups of all of my boxes :-/
But you still have to backup your data anyhow and if one of your drive fails you better replace it, so the time consumed is the same.
