Originally Posted by
ricktas
i use a NAS as well (Network Attached Storage). Mine is a RAID array of 3 x 4tb hard drives. What happens is data is written across all three drives with a check-sum. So that if any one of the three drives dies, I can just buy and insert a new drive and all my data is still available, even that which was lost on the drive that died. A RAID array is RAID (Redundant Array of Inexpensive Disks or Drives, or Redundant Array of Independent Disks)
To simplify how it works using a checksum. My checksum might be 9. As the data is written across the drives it might write 4 to the first drive, 2 to the second drive and 3 to the third drive (adds up to 9). So if a disk dies and I put a new one in, the system goes OK, I have a 4 and a 3, so the missing data is a 2, because I know it has to add to up 9, and the NAS rebuilds the missing drive, onto the new one, completing my data.
This is a very simplified look at the way NAS works. And it depends on the type of NAS you get. Some are simply one hard drive, partitioned, or two drives that are just a copy of each other. Which is basically what your external drive is, but once you set a NAS up in a RAID array you are creating a more secure storage type, that copes with a HDD failure. The biggest issue with a RAID array is the controller, if the controller dies or is damaged, and it loses the checksum, then your drives are not retrievable. So like other backup systems mentioned above, it is still definitely worth having another backup source.
Another benefit of a NAS (network attached storage) is the network bit in the name. You can assess your NAS from anywhere, if you set it up with internet access. So if I have a file on my NAS that I need and I am interstate, I can login to my NAS over the net and get the file. Eg. Maybe I am showing some people photos, and one mentions 'oh I know this place, there is a boat ramp near here, that my grandfather used to take me fishing from'. I have photos of it, but not on my computer with me. Easy.. login to the NAS and use the internet to access the boat ramp photos the person is mentioning. So it has advantages over and beyond an external hard drive plugged into your computer.
As well as my NAS, I have portable external hard drives that I backup to regularly and keep at my work. I used to keep them at a friends, but they changed jobs and started doing FIFO work and it became too hard to get access to the backup when I wanted it.