Advice needed: is a NAS configured as non-RAID a good thing?


I have a NAS on my desk, configured as RAID; 2 mirrored disks. And several external USB disks as well.
My data are somewhere between 10 and 20 TB, partially backed up.

I’m thinking the mirrored NAS isn’t a good thing, as, if I damage it (e.g. let it fall), both disks can become broken and my data lost. But with the amount of data I have, backing thrice is also not a viable option.
I’m considering getting rid of the RAID in the NAS and backing both its disks up on external USB drives so data on the NAS would exists at different physical location, twice.

Usually, NAS are configured with RAID and I bet there’s a reason for that (?).
My concern is: can NASes be used reliably without RAID (as long as backups are up to date elsewhere) or it’s a bad idea?
Anyone having experiences with that?

when you buy a nas, you need to buy the same nas again, to make the backups…
yes nas with mirror raid are pretty useless to me.
a real nas must have at least 3 disks to make a raid5. then they become interesting.

Thanks for your answer.

When I bought my NAS, around 2 years ago, I didn’t had either the money nor the experience to “make it right”. It was my first NAS and I’ve next to never used RAID (I knew its meaning and use, but never used that privately).
So I bought one with only two disks, to become familiar.
Today, I can’t see the point of buying the same NAS again, as it would be a 2 years old model (newer ones would be different and I don’t feel I’d need one)*. Also, I believe I have enough USB disks to have backups on them; I bought them for that.
I’m not planning in buying more stuffs right now, just which path is better between (1) a NAS with RAID and other USB drives (original and backups, but not mixing USB and NAS drives) or (2) a NAS without RAID and backups on USB disks.
Option 2 would allow me to have more space for sharing on other computers as well, but I’m not sure a NAS is designed to work non-mirrored.
Option 1, well, I can lose both original and backup in the same event.

  • Someone gave me an older NAS, but I don’t count it in this question.

So it implies you’ve successfully used a NAS un-mirrored and it’s supported?

if you can make the two disks visible separately (it depends on the nas)
then I would use one disk for storage
and the second disk using an app on the computer, make an incremential backup
at regular intervals, automatically.
otherwise, make one big disk with the two disk, but if one fails, the whole raid is dead
so you must have backups of your big disk.

A backup of the first disk? Then I’m back at square one: if I break the NAS by letting it fall (or get a virus, or other things), both the backup and original data are lost. And that’s basically the same thing as having RAID.

Yes, that would be my 2nd option (all the NAS backed up on separate USB disks and, if one disk fails, I take back from USB backups).
The whole question is, is non-RAID a good idea for a NAS, and supported, for a long time?


It comes down to how important is the data to you and how much would it reasonably cost to reproduce/replace.

I’ve had a NAS with RAID in the house for 15+ years, its evolved from what you had, RAID 2, to RAID 5 and now to RAID 6 (with an additional separate RAID 5 for critical data and some cold storage and cloud storage for data that is irreplaceable). I’ve had RAIDs fail in the past which is why I’m where I am now.

If you go for a RAID 0 (stripe) then you are increasing your chance of data loss, this is usually only done for speed using data that is of little importance but it is a legitimate use of a NAS as long as it has connectivity that allows for the throughput otherwise you’ve just go a slow large external disk with twice the failure rate.

If your data is infrequently accessed then I’d consider an external hard drive dock that you can physically plug drives into, move some data to, then unplug (I use this). You can then store those disks away somewhere safe and pop it back into the slot if you need the data.

no I said incremential backups. you save only datas that have been modified since last backup, this way you can have months of backups on the disk and come back to the date you want.
search for incremential backups on internet.
if you have a mac, the system app doing this is called “time machine”

Those are mostly private files, like pictures, digitalised tapes, and so on. For things I can recreate (e.g. virtual machines), I usually don’t even back up (or merely).
Here, it’s about things I spent much time to make/modify or things I can’t find any longer. All importants to me, privately.

Hard moments, yes.
Have you had external USB drives in your setup along with your NAS?
I bet if you have only NAS devices, RAID (not 0) is mandatory for backups, while, with USB drives serving the same purpose of backups, you can have RAID 0 in the NAS and a backup on the USB drives (a different setup, and my actual question).

I won’t choose an option with no backup at all. With the option using RAID 0, I’ll backup my NAS on some of my external USB drives; the benefit being I could break my NAS without losing data (as opposed to having RAID 2 where both disks could fail at the same time) and also serve more data from the NAS.
As this is a frightening path, I’m curious as to whether you got good experiences with that, but I’m guessing you had a different configuration than mine.

Actually, I have around 13 USB hard disks laying around; I don’t use a dock but a USB hub and can use them all at the same time (if needed). Also, they already all have a case.
Some are “frequently” accessed and some not; and it depends on the period in time. Not very planned :sweat_smile:

Thank you for your advices.

Right, I overlooked that.

Even incrementally, if one breaks his/her NAS, both the “standard” and “incremental” data will be lost.

No need, thanks, I fairly well know about that :wink:
It’s just I didn’t read the “incremental” word in your answer.

Using it since 10.5 :wink:
(but will have to set it up otherwise with my complex setup).


if you use a nas without the mirror raid, for me it’s like two independent drives.
if one is dead, use the other drive to restore the data to the other.
if the nas is dead, open the box, extract the good hard drive and install it in another sata box and use it to restore datas to another one
always have the same datas on (at least) two different drives at the same time.
if your nas gets striked by thunder, both drives may be dead at the same time…

I’ve been researching the use of a NAS so this thread interests me. From what I understand a NAS with two discs in mirrored configuration just makes an automatic copy of one of the discs to the other. This is useful if ONE of the drives fails in which case you would have a complete backup of it on the other drive. This to me seems equivalent to having two external USB drives you are copying the data to, although much easier because it is automatic.

Although not true RAID, it doesn’t seems “useless” from from a backup standpoint.

What am I missing?

Which is why I don’t see the point of having both disks mirrored if I still must do a third backup for the same data, and the start of my question :wink:
(and I agree with all the rest you wrote, but it’s not relevant for my question)
Thank you.

Correct. And, as far as I know (since it never happened to me yet), when you put your brand new replacement disk, the NAS automatically recreates the clone for you.

Not useless, correct, unless something damages your NAS (like you let it fell to the ground or it gets hit by thunder). If both drives have a problem from the same event, both the original data and backup are gone.
That’s why I’m wondering whether I should backup without RAID (that is, set both drives in the NAS as independent and backup their content to other USB drives). Is that a viable, supported in the long run, option?
Given the amount of data I have, backing up thrice can’t be considered.

Yes, of course.

That entirely depends on your needs and intentions.

A RAID can have a positive effect regarding speed (even though the network often defeats this purpose since we’re talking about a NAS). In case of a disk failure one can continue working, letting the RAID repair itself with a new disk. Depending on the type of RAID there are some pros, cons and limitations.

With a “non raid NAS”, it might take you many hours (or even days) to restore data from an external backup until you’re up&running again.

However, a RAID never is a backup. It doesn’t prevent you from a Virus, (drive) software errors, user errors (accidently deleted files), … Data that is important to you needs to be backed up to more locations. One copy should be “not connected” (to the NAS, to Internet or other devices) and be stored in a different location (e.g. at work, in a bank safe, at your mothers/brothers house, …)

Why an “external backup”? Just in case of a fire/water/whatever destroying your house - it would be sad to have both NAS and backup there gone. Oh… and never transport both “laptop and laptop-backup” (or NAS and NAS-backup) at the same time. A friend of mine happened to do that and left both in his car… and both got robbed from there.

The “mirrored” one is not a third backup… you then only have the “NAS (with RAID)” and a first/single backup!

Not necessarily three backups. But 3 copies (the “productive data”, and 2 backups - in different locations) is what I personally do - at least for the most important and precious data.

1 Like

Don’t confuse RAID with Backup. RAID is not meant as a backup mechanism, it’s to keep your data available in the case of a drive failure. You still need (at least one) backup, preferably one that can be taken off site.


Well, 3 copies is still going to be a problem; that’s why I’m considering (and now am convinced I’ll do) removing the RAID in the NAS and using 8 TB rather than 4. So I’ll have two copies (one in the NAS and one across several USB drives).

Thank you; helpful hints.

This is the key of my confusion, indeed. I’ll choose the path of removing RAID.
Thank you.

We always consider the 3-2-1 backup rule.


I’m sure it’s a great rule, undoubtedly.
In my case, 3 copies would represent between 30 and 60 TB of data, for a private use. That would use a lot of USB drives and money (I can’t imagine how I’d set that up).

Forum for Xojo Programming Language and IDE. Copyright © 2021 Xojo, Inc.