Recommendations for long term storage: RAID or ??

Started 6 months ago | Discussions
Sean Nelson
Sean Nelson Forum Pro • Posts: 13,902
Re: A few corrected things

Chris Noble wrote:

afterburn wrote:

RAID is not backup.

Wrong. Many backup systems, on-premise and in the Cloud, are set up as RAIDs.

RAID organized with redundancy only protects against one kind of failure: a disk failure. If a company is using a single redundant RAID system as their sole backup, then they are ignoring a LOT of other risks to their data and woe be their IT managers if some other failure renders the data useless.

It is possible to use an RAID system that's independent of the system being backed up to store backups. In other words, to make a copy of your critical data and store that copy on another independent RAID system.

But without making that distinction it is, IMHO, irresponsible to suggest that RAID "is a backup".

Many backup systems, on-premise and in the Cloud, are set up as RAIDs.

I think it should be pointed out that providers of cloud storage don't provide any guarantees as to the reliability or availability of their services unless you're prepared to pay quite a lot of coin.  The consumer cloud services have no liability if they loose your data, so it wouldn't surprise me if the only thing they do with it is to slap in on a RAID system and hope for the best.  Why spend more money than they need to?

WryCuda Forum Pro • Posts: 10,275
Re: A few corrected things

afterburn wrote:

Sigh...

I'll say it again: RAID is NOT backup. It just isn't. Just because storage systems used for backup can be using RAID does not make that any less true. Please do not pretend otherwise. There are enough people on here that don't have a clue about the difference. Please don't insult my profession.

This seems to becoming a fixation, someone described it as a religion...

RAID protects against a limited subset of failures, but opens the way to several avenues for disaster. it’s obvious that you need more than RAID if you want security.

Having two HDDs just about guarantees that one of them will fail. 

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SC489 Senior Member • Posts: 1,229
Re: A few corrected things

afterburn wrote:

Chris Noble wrote:

afterburn wrote:

RAID is not backup.

Wrong. Many backup systems, on-premise and in the Cloud, are set up as RAIDs.

RAID is just a technology that can be used to mitigate the risk of data loss caused by hardware failures of physical storage devices aka harddisks.

Your convoluted sentence can be replaced by the word "redundant". And it's not just that; some RAID schemes provide redundancy, but some provide faster I/O.

With that out of the way,

Hopefully.

Sigh...

I'll say it again: RAID is NOT backup. It just isn't. Just because storage systems used for backup can be using RAID does not make that any less true. Please do not pretend otherwise. There are enough people on here that don't have a clue about the difference. Please don't insult my profession.

I agree. A common mode software gremlin or malware will be replicated across the RAID discs. The only way to recover the OS then is to recover from a backup image.

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Katamax
Katamax Regular Member • Posts: 101
A copy, by itself, may or may not be a backup

Billiam29 wrote:

... A point-in-time copy of data that exists independent from the status or functionally of the data's source (system).

If that "point in time copy" is on an external HD disconnected from the computer with your data on it, sitting next to it on your desk, and if an operating system bug or malware wipes stuff from your computer, that copy is a backup. If both items are in your basement office which is flooded, that copy is not a backup.

What can be called a backup depends on the adverse conditions one is attempting to protect himself from. The more the better, before a point of diminishing return.

a_c_skinner Forum Pro • Posts: 10,138
Re: A copy, by itself, may or may not be a backup
1

Although backup threads always end like this you may have helped me to respond positively having thought more than I usually do.

Backup is a strategy.  Without the strategy it is just copies of your data.  As ever you devise strategies to meet plausible threats and the less plausible and the less catastrophic the less you prepare to meet them.

I work with files on a work station, then file them on a NAS.  I move the originals to a folder labelled "To delete".  When I backup the NAS I clear this folder.  I've several backups.  Until recently my off site ones (two sets) were 100 miles away, but that is too inconvenient so my protection against a widespread catastrophe is reduced as they are now two miles away but they will get rotated more often.

RAID isn't part of my strategy.  I don't need the continuous up time or speed that are its strong points, so I don't need it.  I can manage easily for a few days during which I buy new NAS, retrieve the backups and restore them.

Cloud won't work for me as I've a very big volume of data (3Tb) and a slow internet connection (soon to be 1Gbit/s so who knows?).

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Andrew Skinner

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Sean Nelson
Sean Nelson Forum Pro • Posts: 13,902
Re: A copy, by itself, may or may not be a backup
1

a_c_skinner wrote:

Backup is a strategy. Without the strategy it is just copies of your data. As ever you devise strategies to meet plausible threats and the less plausible and the less catastrophic the less you prepare to meet them.

That's actually a nice summary.   I think the thing that derails most people is their laser focus on avoiding disk failures, hence the obsession with RAID.  But in my experience as a home user disk failures actually aren't where I've had my issues.  My most frequent cause of data loss has been user error, and I've never had an internal disk fail in well over 3 decades.

Disk failures were a big deal when I ran a datacentre because of the uptime requirement and because the sheer number of drives involved.  So of course we used RAID.   But that sure as heck didn't stop us from making backups as well.  They were crucial because our most frequent need for data recovery came from - you guessed it - user error.

kelpdiver Veteran Member • Posts: 4,395
Re: A few corrected things

SC489 wrote:

I agree. A common mode software gremlin or malware will be replicated across the RAID discs. The only way to recover the OS then is to recover from a backup image.

or that snapshot.   guess where that's available?

a_c_skinner Forum Pro • Posts: 10,138
Re: A copy, by itself, may or may not be a backup

Thank you.  Yes. I've had one disk fail ages ago. I had the contents on 3.5" disks! I've lost some raw files through carelessness. Not lost the processed images, but my aim is always to keep the raw and JPGs from the camera.

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