RAID is not a backup?

Jiggens · Aug 12, 2016

Hi all,
I have recently experienced my first catastrophic drive failure where data is irretrievable.. lost everything I had stored over ~21 years and 10+ PC rebuilds.. pretty devastating, but my own fault for never having bothered with a real backup. As such, I am now looking into something a bit more secure to make sure this doesn't happen again.

Since I tend to use multiple small (60-500GB) SSD's as my internal drives for boot, programs, games, etc (stuff I can reinstall easily and doesn't really need to be backed up), I don't have enough SATA ports left to run a large storage drive-
I had kind of settled on my storage (photos, music, documents, etc) being a 2TB external drive backed up to a 2bay external RAID enclosure running 2x2TB drives in a RAID1 mirror.

But doing quite a bit of research before I spend over $500 on this, I see it popping up everywhere that RAID shouldn't be used for a backup, and can't for the life of me figure out why the hell not.

I don't have kids or idiots running around my house, literally nobody except me has access to my computer, and I'm not (much of) an idiot myself, so I'm not too worried about accidental deletion.
My computer is in the back of the garage, running off a power board with individual surge protectors on each outlet, with nothing but bricks and concrete around it, and I don't really plan on setting my house on fire any time soon anyway, so I'm not worried about damage.
I have very careful browsing habits and only use my PC with trusted programs, so I'm not particularly worried about virus.
It's literally just drive failure that scares me, because in 21 odd years that is the only thing that has ever caused me to lose data.

Could someone please explain to me why I shouldn't be using RAID1 like this to back up my external storage drive?
And would it work if I went the other way round, using the ext-RAID1 as my normal storage device and then backing it up to the external drive with no mirror of the backup? I imagine this would work but would make everything a lot slower having my storage on a mirror RAID with spinning discs instead of an SSD.

Any info on the situation will be much appreciated.
Thanks.

01111111 · Aug 12, 2016

Raid can be a backup storage device the real meaning is Raid does not replace backups.

A raided device for backup is an excellent place to keep your backups, protecting you from a single drive failure. More importantly you need to setup alerting so you know when a drive fails and replace it ASAP. You can use this setup either way.

The idea with backups is the more places you can put it the better.

Saga Lout · Aug 12, 2016

SAhort answer - the only safe system is one that doesn't include RAID at all. That's nly my opinion but in a domestic or small business system, tere simply is no need for RAID because when it falls over, it takes everything down with it.

The safest backup is a manual one - the frequency is your choice - and made to a separate external drive which is then stored in a fireproof box until the next backp date.

Jiggens · Aug 12, 2016

01111111 :

Thanks, that is about what I was thinking in the first place before I ran across a bunch of articles saying to never use RAID for a backup device.
Most of the external enclosures I have been looking at have alerts, not instant email alert or anything, but will flash a red LED if there is a drive failure, and I use my computer every day and would likely notice within 10hrs (more often than I check emails anyway hah) if something went wrong. I've had probably 3 drives in total fail on me in over 20 years, so I would be pretty unlucky to have both RAID drives fail in that time frame.

Jiggens · Aug 12, 2016

Saga Lout :

I would be doing my backups manually as there are typically only certain things I really want to keep rather than a full copy of the entire storage drive. Could you please explain how or why a RAID failure, especially a RAID1 mirror, would take everything down as this is what I'm having the most trouble wrapping my head around and losing everything like that is basically worst case scenario..

Cousin IT · Aug 12, 2016

Saga Lout :

I am confused by this. "The only safe system doesn't include RAID" I am the IT manager at a small business. About 150 workstations and 5 different physical servers (about 30 VM's). I don't understand how we would be safer if I did not have all the servers on RAID volumes. I have had hard drives fail before and it does not take everything down, in fact, nothing goes down. I replace the hard drive and the users do not even know it happened. How would it be safer to not use RAID?

As for the question, the reason people say RAID is not a backup is for all the reasons you stated. Physical damage to the appliance, or viruses. If you are 100% sure you are protected from those things, then RAID will protect you from a single hard drive failure, but that is a gamble no matter how careful you are. No one plans on burning their house down, but it happens. No matter how careful you are, if your computer is connected to the internet, there is a chance of malware.

Jiggens · Aug 12, 2016

Cousin IT :

So if the only thing I'm worried about is drive failure, the RAID backup should work as a solution for my specific intended purpose?
I understand that sometimes things can happen that I won't have control over, but I do everything in my power to reduce the chances of these things, so it's a calculated risk I'm willing to take. As I say, in over 20 years the only thing that has caused me any kind of major data loss so far is this recent drive failure, so at least for the moment that is the primary thing I am looking to protect against.

Cousin IT · Aug 12, 2016

If all you are worried about is drive failure, in my experience, yes a RAID 1 volume will technically work as backup. Mr 01111111 (hope I got all the 1's) is very correct that you need to make sure you have some sort of alert so you know immediately if a drive fails, so you can replace it immediately. There is still that small chance you could have both drives fail, although it is a very very small chance.

viewtyjoe · Aug 12, 2016

Saga Lout :

A single hard drive failure is rarely enough to kill a properly set up RAID volume. I'm not a fan of RAID 1 because you tend to buy your hard drives in pairs then and then said hard drives tend to fail in pairs. A properly built NAS using RAID 5 or 6 should add enough redundancy to survive the typical drive failure experience seen in consumer/small business usage.

That said, you need to monitor said NAS for drive health and possibly keep a spare unused drive or two handy to fill in on the chance of drive failure to minimize the chances you eat multiple failures while you're trying to rebuild the array.

The idea of backing up to a single detached storage device that gets locked away for periods of time is begging for issues. It's a literal single point of failure that you have no visibility on outside of when you write data, which gives zero guarantee that you can recover that data. Visibility, proper care and vigilance are the order of the day when it comes to data protection. The hard drive that isn't being monitored is the hard drive that fails unexpectedly, taking your backups with it when you try to recover them after the main drive(s) fail.

Cousin IT · Aug 12, 2016

viewtyjoe :

Saga Lout :

A single hard drive failure is rarely enough to kill a properly set up RAID volume. I'm not a fan of RAID 1 because you tend to buy your hard drives in pairs then and then said hard drives tend to fail in pairs. A properly built NAS using RAID 5 or 6 should add enough redundancy to survive the typical drive failure experience seen in consumer/small business usage.

That said, you need to monitor said NAS for drive health and possibly keep a spare unused drive or two handy to fill in on the chance of drive failure to minimize the chances you eat multiple failures while you're trying to rebuild the array.

The idea of backing up to a single detached storage device that gets locked away for periods of time is begging for issues. It's a literal single point of failure that you have no visibility on outside of when you write data, which gives zero guarantee that you can recover that data. Visibility, proper care and vigilance are the order of the day when it comes to data protection. The hard drive that isn't being monitored is the hard drive that fails unexpectedly, taking your backups with it when you try to recover them after the main drive(s) fail.

I very much agree with this, however your current 2-bay NAS will not allow for this.

viewtyjoe · Aug 12, 2016

Cousin IT :

I am not a fan of 2-bay NAS devices for this reason. I wouldn't look at anything less than a 4-bay if I was looking to build a serious backup device.

Cousin IT · Aug 12, 2016

viewtyjoe :

Again, I don't disagree with this, I was simply answering the question based on the hardware he currently has and was asking about. Assuming he doesn't want to purchase a new NAS, RAID 1 is his only option.

DSzymborski · Aug 12, 2016

Honestly, I'm not sure the original poster needs this kind of setup. From what I see at the top, he'd be served just fine with a simple automatic cloud backup supplemented with a secondary hard drive and periodic optical disk backups.

Jiggens · Aug 12, 2016

viewtyjoe :

Unfortunately price is a major inhibiting factor in this for me, the drives I would be using are actually 4 second hand reformatted drives from an old build, all the same make/model but all seen different amounts of usage, so would hopefully not fail at the same time, and if one did there are 2 spares of the same type I could use for replacements.
I would prefer NAS if I could afford it, unfortunately the prices for just about everything I can find are more than double the cost of an external RAID enclosure.

viewtyjoe :

Perhaps not as ideal as a NAS box, but as far as monitoring, the longest I generally spend away from my PC is around 10 hours at a time, so I should be able to notice any drive failures pretty soon after they happen, and I will have 2 spare drives ready to rebuild onto.

viewtyjoe :

That's the one I learnt the hard way with my recent failure and is why I started looking into having the backup mirrored in case of a drive failure, so basically I would have the local copy plus TWO backups, albeit stored in the same enclosure.

Cousin IT · Aug 12, 2016

DSzymborski :

Purchasing cloud storage will cost money and it seems he is trying minimize costs. There is no way I am backing up 2tb of data to optical disks, this would be very tedious.

Given the hardware you currently have, trying to protect against a single hard drive failure, RAID 1 in your current NAS is going to be the best option. Yes, there are better options for backup, but not without additional costs.

Jiggens · Aug 12, 2016

Cousin IT :

Do not have a current NAS but that basically covers it otherwise. All that it will cost me is $89 for the enclosure (https://www.pccasegear.com/products/35446/hotway-hur5-su3-2-bay-3-5in-raid-enclosure) and a new external drive should put it to around $200 all up which is just about all I can afford, at least for now.

Thanks to everybody for your help, that's just about all I needed to know. Unless anyone has suggestions for a better solution that would be around the same price range, I won't be able to afford anything more for at least a few months unfortunately.

Saga Lout · Aug 12, 2016

My comments were based on the principle that no backup in the same box as the original can possibly be considered safe. I've heard several tales of RAID arrays which failed completely and actually witnessed one. It has to be said that my customer on that occasion may have caused the total failure himself in trying to recover from the initial disk failure and before calling me in.

I wouldn't trust the Cloud either because I prefer my personal data to be under my control a not someone else's. Maybe I'm just an old cynic but for me, the backup is in a safe which won't melt in a fire quite as quickly as my PC and server cases if the worst were to happen.

Cousin IT · Aug 12, 2016

Saga Lout :

He doesn't have his backup in the same box though. He uses an external drive as the primary storage and uses the NAS as the backup.

The comment I am confused by is where you stated "in a domestic or small business system, there simply is no need for RAID because when it falls over, it takes everything down with it" My experience has been much different. Yes, there is the possibility of an inexperienced user making a mistake, but this is not the fault of the RAID volume, it is the users fault. If maintained properly, a failed hard drive will not take everything down, that is exactly the point.

Yes, appliances can fail, but so can the single hard drive in your safe. And even if the appliance does fail, with a RAID 1 volume, the data is easily recoverable, if your hard drive fails, you are screwed.

RAID is not a backup?

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