A drive could fail the day you put it in the computer or 10 years after you buy it. It is up to you if this is worth the risk. I have never had a disk failure in 11 years of owning a computer. I am lucky. A friend of mine has had 3 failures. His data was saved by having a mirror disk, and on one occasion having a backup copy. RAID 5 helps against a single DISK failure. Good practice is to run this RAID with a UPS which reduced the risk of electrical failure as a problem. Yes, and offline backup is the only way to really protect your data fully. Considering you want 5 TB of space, I would guess that you have a lot of video, cough, cough content. This is not family photos and precious data. I do not store my pictures all on a RAID, I have an external drive. having 5 TB of space for stuff, and then 5 TB of space for offline backup is not feasable in your case. If you insist on having all that space, do not use any form of raid at all. Just use the drives individually. If a drive fails. you just lose that data and the other drives keep humming along like nothing happened. If you want to potentially protect yourself in the case of a drive failure then sacrifice 931 GB of space and go raid 5. I have had good luck with it. Some have not. But, JBOD or BIG or RAID 0 are all very bad options especially with that many drives. The potential of failure in those cases is multiplied by 5. And noone out there can tell you if/when your drive will break. I just assume I will lose one eventually and plan for it.