In article , Sandman
wrote:

It sounds to me that he is looking to consolidate the 4TB of image
files from the several external HDs he is currently using, and a
good RAID with some redundancy can provide that storage with easy
retrieval. He didn't ask anything about back up, that is a
different question. That said having the RAID as part of a network
server is also a viable possibility.

raid is high availability and most people don't need that.

raid is not a backup.

Uhm, a mirrored raid most certainly is backup, saved me a number of times.

raid is not a backup.

raid is high availability.

if you have a hardware failure in a raid, you can keep working while
you replace the failed drives. that's very useful for a business who
won't want to turn away customers while the restore takes place.

for a home user, it's not a big deal if there's a little down time
while a restore takes place. it's annoying, but it's not the end of the
world. go out to dinner or play tennis or something.

raid is *not* a backup because it's still a single copy. you're only
covered if there's a single drive failure. if you corrupt a file or
accidentally delete it, it's gone. if multiple drives fail at the same
time and it's more than you have redundancy, you lose all.

it's also not unusual to have a hard drive in a raid fail and when you
replace it, another drive fails *while* it's working hard to rebuild
the redundancy. remember, it's going to work non-stop to rebuild. if
that happens before it's done rebuilding, you lose everything. this is
more common than one might think because people frequently buy drives
in a group and load up the raid, which means they come from the same
batch and are likely to fail around the same time.

I currently have a 12TB RAID5 NAS on my desk, all data backed up for
hardware failure.

not unless you have *another* 12 tb drive.