Raid 5 - the best for budget redudancy?

boomstick1 · Jul 6, 2013

Is the best for protecting your data on a budget, given you have an SSD for programs and applicants (i.e., all i need on these HDDs is read performance).

Everyone keeps saying that RAID isn't back up. Can you explain why? I know it doesn't protect against virus, or human errors, or things like electrical surges, etc. But, given my budget, I'd like to bite the bullet and just live with these risks. What I want to protect against is a hard drive failure say 12 months from now.

RAID 5 seems like the best ration. I'd be using WD Reds.

What do you think?

Can I add drives to my array later on
?

Like buy 3 drives now and raid5 them, and then add a drive later and add it the array (3 working drives, 1 redundant)
Thanks.

USAFRet · Jul 6, 2013

RAID is not a backup. Everything lives in one box.

A cheaper, faster, safer alternative is an external USB drive, turned once or twice a week to back stuff up.

geofelt · Jul 6, 2013

The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years. SSD's are similar.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware,raid controller failure fire, theft, etc.
For that, you need external backup. If you have external backup, and can tolerate some recovery time, you do not need raid-1

boomstick1 · Jul 6, 2013

USAFRet :

Could you please explain your claims here. I'm very interested in them.

"Everything livers in one box" -- as I said I'm OK with risking case fire, electrical what not. I want to protect against Hard Drive failure.

How is a external USB drive cheaper than have RAID 5? External USB drive needs the same size as what you're backing up. With RAID5, you can protect 5 HDs with just 1 additional drive.

USAFRet · Jul 6, 2013

boomstick1 :

OK...what specifically are you wanting to back up or protect? User data? Homework, resumes, family pics? Movies?
Or are you looking to preserve the entire software install, including user data? The OS, all applications, and user data.

What is the expected downtime? For a public facing production environment, where you need it back online now, a RAID situation is the answer. Yank out the bad drive, swap in a new one.

For a non production environment...the OS and applications can be reinstalled easily. Or clone the whole OS/application drive to a VM or other backup mechanism, and restore to a new drive if something bad happens.

If you're down for 24 hours in a production environment, some one is getting fired.
If you're down for 24 hours in a non production environment....meh.

Do you like using your PC, or managing the PC?

I have all my personal, irreplaceble stuff backup in multiple places. A drive on another PC, and a separate external drive. If anything bad happens (fire/flood/whatever), I just have to grab one or the other, and go. And in case of theft, one of those drives is not readily seen.

What are you hoping to accomplish with this RAID5?

boomstick1 · Jul 6, 2013

Thanks for all the thoughtful, well-written feedback.

I use my drives for media, and it's certainly a non-production environment.

I'm just trying to protect myself against one and only one possible future situation: in 3 years one my hard drives just happens to die. I have 2.5 TB of movies on that drive that'd rather not lose. If I Loose them, then it's OK, but not ideal. If it costs me $140 to buy 1 additional HD to set up a RAID and protect against this I might as well.

boomstick1 · Jul 6, 2013

At this point I'm leaning towards still getting the RED drives cause of the quality parts and warrenty, and then backing up my important docs (papers, pictures, music) on a laptop or just duplicate them on another drive in my rig....and then just risk losing movies and TV shows down the line.

geofelt · Jul 7, 2013

If you go to raid-5, you will need 3 drives.
Then, you will have fault tolerance for one drive.

If, instead, since you are on a budget, you dedicate just one drive to external backup it will cost you less.
In addition, a backup will contain compressed images of your prime drive so it will take less space to back up than the original drive.
Take a image copy of your original drive. Then, as you add media do an incremental backup.
This way, your performance will be better for normal operations, and the backup can happen in the background.

boomstick1 · Jul 7, 2013

Thanks!.

So I might as well do Raid 0 then on my drives? Better than no raid?

geofelt · Jul 7, 2013

boomstick1 :

NO!!
With raid-0, a failure of either drive will lose all your data.

Raid-0 has been over hyped as a performance enhancer.
Sequential benchmarks do look wonderful, but the real world does not seem to deliver the indicated performance benefits for most
desktop users. The reason is, that sequential benchmarks are coded for maximum overlapped I/O rates.
It depends on reading a stripe of data simultaneously from each raid-0 member, and that is rarely what we do.
The OS does mostly small random reads and writes, so raid-0 is of little use there.
There are some apps that will benefit. They are characterized by reading large files in a sequential overlapped manner.

boomstick1 · Jul 7, 2013

boomstick1 · Jul 7, 2013

Thanks for the feedback. I've been very busy on this forum for the past day or so trying to figure it out.

I really am not worrying about accidental deletions or intense viruses. Perhaps everyone thinks I'm foolish, but with avast and careful web browsing I've never had anything close to a virus that would destory a HD. Thus, the only thing left that I am really worried about is one of these hard drives failing---anyone who reads user reviews will see that maybe 1 out of 20 HDs fail in the a year or so. So, I want RAID to protect against that.

I have no problem replacing a failed HD (with an RMA it will probably free).

I don't have the budget to make a copy of all my files. Hence I like the ratios provided by RAID 5.

To my knowledge WD RED drives are very good at recovering an array that has lost a drive.

geofelt · Jul 7, 2013

You might like this somewhat outdated report on hard drive return rates:
http://www.behardware.com/articles/881-6/components-returns-rates-7.html

To make a backup of a hard drive, you need only a second hard drive. And... since data will be compressed, you will be able to backup more data on it than the original space.

To use raid-5, you need to spend more to buy 2 extra exact hard drives.
And... look at the return rates for motherboards too. If the motherboard fails, there goes your raid-5 too.

boomstick1 · Jul 7, 2013

Geofelt,

Thanks for the link.

I've said that I cannot afford buying backup drives for each drive (and compression wouldn't make enough of a difference to help my budget). Your sentence about "spending more money" to buy drives for RAID5 contradicts your sentence above where you boost have a drive duplicate solution. This option is much more expensive that RAID5, hence my interest in RAID5.

ALl the failure rates seem pretty low. I can't decide if RAID is a good way to protect against HD failure.

USAFRet · Jul 7, 2013

boomstick1 :

To safeguard 1 drive worth of data with RAID5, you need 3 drives. 1 + 1 + parity.
To safeguard 1 drive worth of data with a simple external, you need 2 drives. 1 + copy.

boomstick1 · Jul 7, 2013

USAFRet :

But with a 3 drive RAID config, you get 2 drives worth of data. A 1:3 ratio as opposed to a 1:2 ratio. I'll probably wind up with 6, 3 TB drives in the end, for 15 TB of data.

geofelt · Jul 7, 2013

As I understand it, a raid-5 system using, for example 3 1tb drives would give you a useable capacity of 2tb. An array of 4 such drives would give you a capacity of 3tb.
In either case, your fault tolerance would be one drive.

But, failure of the raid controller would be catastrophic.
A corollary to Murphy's law says that if you have any single point of possible failure, that is where you will fail first.
Nothing wrong with raid 5 for faster recovery. But for data you can't lose, you need external backup.

geofelt · Jul 7, 2013

I see your point; yes, the more drives in the array, the more economical it is to guard against loss of one drive.

But, If disaster strikes, can you tolerate losing 15tb of data?

boomstick1 · Jul 7, 2013

Thanks for the replies. I'm learning a lot from you guys.

Not sure what you getting at with Murphy's Law. Yes, of course, if you have only one point of failure it will be the first thing to fail.

I see your point: with RAID I either lose nothing or everything. With a bunch of normal drives if one fails then I just lose that data.

Still, you think failing to rebuild an array, or getting a nasty virus, or losing a mobo is a very live possibility?

All this is leading me away from WD REDs towards WD Greens---esp after watching this review http://www.youtube.com/watch?v=QLzWB1wtpPI

USAFRet · Jul 7, 2013

boomstick1 :

The more complexity you add, the greater possibility of failure.

With a simple copy or backup on another drive, and the motherboard fails...no problem.
With a RAID array, and the motherboard fail...oops...all is gone.

boomstick1 · Jul 7, 2013

And motherboard failure is a real thing? I just did my first build and but budget mobo.

boomstick1 · Jul 7, 2013

And motherboard failure is a real thing? I just did my first build and bought budget msi mobo.

USAFRet · Jul 7, 2013

boomstick1 :

Over the last year, I've built maybe 8 PC's for myself and friends. 1 mb died, a Gigabyte. Lasted about 3 weeks. Sure, the replacement was covered under warranty. But if I had a RAID array slaved to it...

Rare, but it happens.

boomstick1 · Jul 7, 2013

OK. Done. Not doing RAID. Thanks for all the help everyone.

Now I'm torn between WD Reds and WD Greens.

smitbret · Jul 8, 2013

Jumping in late, RAID is still better than nothing. I run an 8TB RAID 5 but backup the critical stuff to a 2TB external. My DVD/BR rips can always be ripped again and they are the biggest part of the storage.

Why not use a software RAID like FlexRAID or SnapRAID instead of hardware? Looks like it would fit your needs much better.

#1 - You can use whatever drive(s) you want. They don't have to be the same size, brand or anything and you'll be able to use all of the space on all drives even if they are different sizes.

#2 - You can add or subtract drives from the array at anytime without having to completely break the array up and start over. Wanna add another 2TB drive? Just import and update. Boom, your RAID array is 2TB larger and all of your data is still there.

#3 - If you have a catastrophic crash, you only lose the data on the drive(s) that crashed. If you have a 4x2TB array and a data drive crashes and then the parity drive crashes, you still have 2 drives with recoverable data.

#4 - If your motherboard fries, you swap it our and go on your merry way. The RAID info is in the HDDs and is not related to the hardware at all. Lose a HDD controller card? No problem, get a new one.... could be the same or different, doesn't make any difference.

#5 - No need to start with empty drives. If you already have data on them, just import them and the data becomes a part of the array.

Raid 5 - the best for budget redudancy?

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