[SOLVED] Why people use RAID and it is often recommended?

modeonoff

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Jul 16, 2017
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Hello, I know it provides redundancy in case of drive(s) failure. However, we need to buy extra drive(s) to achieve that. We could buy one enclosure and only one large drive as an additional backup which is less expensive than buying more drives for redundancy. So, what is the point of using RAID (such as RAID 5) which is more expensive and not 100% failsafe?
 
Solution
Thanks. On the internet in NAS related forums and youtube, people like to recommend others to use RAID 5. Of course, we don't know their background. Could be somebody who heard form others and just made the same recommendation. That is why I asked in this well established site.
OK, so that would be some context on where you heard this.

With a 4 bay NAS box, a RAID 5, maybe.
It provides physical drive redundancy, in the face of a single drive fail.
And only to keep the data up and accessible, until such time as you can take it offline to swap the dead drive and rebuild the array.

RAID is not a backup. That can't be stated enough times.

Your data ALSO needs a real backup, apart from and alongside the RAID.

When I...

USAFRet

Titan
Moderator
Hello, I know it provides redundancy in case of drive(s) failure. However, we need to buy extra drive(s) to achieve that. We could buy one enclosure and only one large drive as an additional backup which is less expensive than buying more drives for redundancy. So, what is the point of using RAID which is more expensive and not 100% failsafe?
Where did you read that it is "recommended"?

Outside of very narrow range of business level circumstances, it is not.
Especially in the consumer realm.
 
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modeonoff

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Jul 16, 2017
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Thanks. On the internet in NAS related forums and youtube, people like to recommend others to use RAID 5. Of course, we don't know their background. Could be somebody who heard form others and just made the same recommendation. That is why I asked in this well established site.
 

USAFRet

Titan
Moderator
Thanks. On the internet in NAS related forums and youtube, people like to recommend others to use RAID 5. Of course, we don't know their background. Could be somebody who heard form others and just made the same recommendation. That is why I asked in this well established site.
OK, so that would be some context on where you heard this.

With a 4 bay NAS box, a RAID 5, maybe.
It provides physical drive redundancy, in the face of a single drive fail.
And only to keep the data up and accessible, until such time as you can take it offline to swap the dead drive and rebuild the array.

RAID is not a backup. That can't be stated enough times.

Your data ALSO needs a real backup, apart from and alongside the RAID.

When I first got my QNAP, I set it up as a RAID 5. 4x 3TB drives. Later, upgraded to 4x 4TB.

Before long though, I undid the RAID in favor of individual drives.


And further, once we get into larger drives and data consumption, RAID 5 becomes problematic.
When I switched from 4x 3TB to 4x 4TB, I did it one by one, just to see how the QNAP handled that.
There was about 6TB actual data space.

Swapping in the new 4TB drives, one by one, required about 8 hours each time to rebuild the array. So the whole thing took several days.
 
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Solution
Personally, I tend to avoid RAID, partially because I consider a decent backup routine better than Raid 1, and also there is very few cases I consider Raid-0 not the proper solution to any of my needs.

However - a couple of years back I assembled together a scrap computer consisting of 3 trashed 500gb drives (being used in tv recorders but still working) - the rest of the hardware being from like 2006, for the sole purpose of backup (actually located in a wooden cabin far from nearest city).
I first was wondering of using some sort of raid, but I decided to use btrfs because it support joining partitions natively.

Since the computer is low on RAM, I made 3 equal partitions for swap space, that is because in swap partitions in Linux can be set up in such a way that it act sort of like raid - by givin each partition equal priority in fstab file. Beyond the purpose of backup, it's mostly to prove a point - that it can be done.
 
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modeonoff

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Thanks. Am I correct that regardless of whether I go for NAS or DAS eventually, it is better to get two enclosures for two separate independent backups than one big 4-5 bay enclosure with all the drives in it?
 

USAFRet

Titan
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Thanks. Am I correct that regardless of whether I go for NAS or DAS eventually, it is better to get two enclosures for two separate independent backups than one big 4-5 bay enclosure with all the drives in it?
The basic backup concept: 3-2-1 (we've gone over this before)

3 copies, on at least 2 different media, at least 1 offsite or otherwise inaccessible.
 
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