RAID is not a backup?

Raid protects against a drive failure. A backup should protect against fire, theft, accidental deletion......and so on.

Indeed RAID is simply a way of combining disks for increased throughtput and/or resilience. This is different from a backup which is the contingency of  the RAID disk system itself getting damaged, failing,  stolen, or corrupted - any of which will happen sooner or later....

You can have two separate RAID systems where one is set to back up another. In such a case put the two RAID systems as far apart as possible so as to provide some sort of physical separation and contingency. This is what I do.

Simon

How far apart are yours Simon?  Mine are 200 km

At the moment I just have music on the NAS but I need to set it up as a PC backup as well. And then I need to add a separate USB3 drive to backup the music store as well.

Umm, about 10metres... You win 

Thanks for the advice. I have another nas that I can reintroduce to the network and provide belt and braces.

Another lesson: make sure your shelves are big enough.

If you just Google "what is Raid", there is an excellent Wiki explaining in "understandable" wording what it is

Back ups are always an interesting discussion ! In the old days, I never remember anyone saying we should all buy a second set of Vinyl LPs, and store them 100 miles away just in case the first lot got stolen !

Point taken though - backups are made eday these days, the above remark is a bit tongue-in-cheek.

Paul

If you have a detached garage this is a great place for a second NAS, especially if it already has electrical power installed !

Just run a CAT5 network cable into the garage (parallel to the mains cable if necessary*), punch down the CAT5 cable strands into a surface mounted socket and voila  

OK, there was the challenge of feeding the cat5 cable through the underground duct without digging up the driveway, but any electrician worth his salt will come with a trained hampster or gerbil for this  (some of them even use those long cable-draw wires these days, I believe).

Then it's just a matter of setting up a backup job to run NAS to NAS each night... oh, and keeping your fingers crossed and your garage locked.

(* CAT5 running parallel to mains ? - don't worry, it works OK - after all you're not streaming music, you're copying data files... overnight while you're asleep)

RAID comes in several flavors. RAID 0 is not fault tolerant, it is just a way of expanding disks so 1 TB + 1 TB gives 2 TB available disk, Loose one disk and all is gone. .

RAID 1 is disk mirroring , so basically 1 TB + 1 TB = 1 TB but you can loose one disk and add a new one without looosing data.

RAID 5 is RAID setup where the data that is used to restore is spread on all the drives in the RAID set. mimimum 3 disks are required. so with 4 disk you loose 25% , with 3 disk you loose 33% disk but it is fault tolerant so you can loose one disk and replace.

/Kenneth

Everything I have ever read about RAID, regardless of which variation, emphasizes that it is NOT a backup strategy...but merely a fail-over for disk problems.

But of course you can use a RAID setup as a backup. It is just that it is not its own backup.

Very true. 

You could use a PC to rip to it's internal disks and then take a copy to the NAS in the garage. You could then stream from the NAS.

RAID is not a backup in itself, its for resilience and speed. However you can use a raid as a backup location providing the primary copy is elsewhere.

mirroring (two locations kept in sync) may not be a backup, delete something on disk a and it's also deleted on disk b but it depends on the mirror process.

a backup is an independent copy of the original data that's not altered by events on the original source.

My backups are only 3m apart but crucially in oxfordshire that's the vertical separation