Raid Z2 vs 2x raid 0 Servers (One raid 0 and one raid 0 backup server)

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Wally

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Well, my storage is getting full. I currently do NOT have a backup either. My dual socket opteron has been running strong for over a year now. But I need more space and a backup. I was thinking to make my current setup the backup server and creating a new one with raid 0 for the primary. Once all data is transferred, I would make my backup raid 0 as well.

Current setup:

ASUS K8N-DL Dual Socket, Opteron 285 2.6Ghz (Overclocked to 2.7Ghz) Dual-Core, 12 GB RAM, 4x WD Red 3TB, 750 Watt PSU using On-Board sata controllers (Both), 60GB SSD cache, LACP 2 gigabit connections.

In case your wondering, draws an average of 220 watts, not that power draw is a concern.

I was thinking of re purposing a used HP server with dual socket xeon or opteron. Quad or Six cores though.
 

Nick2253

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You didn't actually ask a question, but I'm assuming you want to know if anyone has any feedback on your decision.

(To be pedantic, there is no such thing as RAID 0 in ZFS. It is stripped drives. Saying "RAID 0" implies hardware RAID, which is bad.)

A stripped array is bad on a number of fronts, especially if it holds any kind of critical data. First off, ZFS depends on some kind of redundancy to fix UREs. Without redundancy, ZFS can tell you that a URE has occurred, but it has no way of fixing it. This means that one URE could wipe out your entire array, if it lands in the wrong spot in the metadata.

Secondly, a stripped array means that the failure of any one drive takes out your entire pool. If both your primary and secondary arrays are stripped, then it would take only two drive failures to wipe out all of your data.

With at least RAIDZ1, you would be capable of restoring from a URE. Given the URE rate, you should treat RAIDZ1 as sufficient to protect you from UREs, but not a failed drive.

However, that all seems to defeat the purpose of what FreeNAS and ZFS are trying to provide. To use an analogy, ZFS is like having a whole-home security system, top-of-the-line with all the bells and whistles, but to use it with stripped drives is like never turning it on and leaving the doors unlocked. There's definitely a use case for stripped drives under ZFS in very specific instances (where, for example, it's more important to know that you data in wrong than knowing what it is supposed to be), but this is most likely not it.
 
J

jkh

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However, that all seems to defeat the purpose of what FreeNAS and ZFS are trying to provide. To use an analogy, ZFS is like having a whole-home security system, top-of-the-line with all the bells and whistles, but to use it with stripped drives is like never turning it on and leaving the doors unlocked. There's definitely a use case for stripped drives under ZFS in very specific instances (where, for example, it's more important to know that you data in wrong than knowing what it is supposed to be), but this is most likely not it.
Don't forget the overclocking he's doing... Though, that said, if you're trying to get the most out of your Alienware FreeNAS box, that's practically mandatory I suppose!
 

Wally

Dabbler
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Jan 23, 2016
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Hey Nick 2253,

Your right. I my question was, should I continue to use Raidz2 and have a backup of a stripped array or should I have too stripped arrays where one is the backup of the other. These would be on separate systems. I don't have a lot of money so my thought was that my current server would be 12gb as a stripped array which would be enough space for the foreseeable future and I would purchase 4 more drives to act as a backup. Otherwise, I would have to purchase more drives and as it stands, 4 is out of my budget.

Just to confirm, No Hardware raid will be used. Only what FreeNas provides.

Another note, I would just purchase another drive to add on, but I need to store everything temporarily and I don't think that is doable with what I have.
 

Nick2253

Wizard
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Apr 21, 2014
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1,633
Don't forget the overclocking he's doing...
Oh, dear lord, I didn't even notice that :eek:

Your right. I my question was, should I continue to use Raidz2 and have a backup of a stripped array or should I have too stripped arrays where one is the backup of the other. These would be on separate systems. I don't have a lot of money so my thought was that my current server would be 12gb as a stripped array which would be enough space for the foreseeable future and I would purchase 4 more drives to act as a backup. Otherwise, I would have to purchase more drives and as it stands, 4 is out of my budget.
I think we need to step back to the drawing board to understand what your goals are for this system. While everyone has their own reason for running FreeNAS, it usually boils down to one thing: secure data storage.

And that's really what FreeNAS has been built around. And it's largely what this community has been built around. It's why we tolerate the massive inefficiencies of ZFS, the extra cost for "server-grade" hardware, and the terrible "waste" of hard drive space due to redundancy.

With those things in mind, it's up to you to reconcile what you want to achieve with what you are doing. For example, there's a time and place for overclocking your CPU...and I'm going to say that your main data server is not it ;). Things like zero-redundancy striped arrays are also inappropriate for data storage.

I do understand the desire to save money; believe me! However, I'm going to guess that you wouldn't be using FreeNAS if your data had no value to you. So you have to make sure that you aren't saving a few pennies at the cost of risking your real "wealth": your data. Moving your data, even temporarily, to non-redundant array is a really, really bad idea. It takes only one(!) URE to completely trash your entire backup. Then it's gone, poof, byebye!

Again, it's ultimately up to you how you proceed, though if it were up to me, and we were talking about my data, I would never tolerate even the backup of my data in such a vulnerable setup. Maybe the backup of the backup, but even that's pushing it. Hard drives are so cheap nowadays, so it's extremely easy to get a large measure of security. Is it free? No. But is it worth it because of the value of my data? Absolutely, yes!
 
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