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In search of ... opinions on RAID at home

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barney:
Had a discussion group earlier today - six (6) of us this time - that started out as a football watching event.  As usual, the discussion was alcoholically fueled, and the six (6) of us voiced ~eight (8 ) opinions ... I said it was alcoholically fueled, didn't I  :P?.  (Usually these events are at a table at a bar, but my recent incarceration by infirmary incompetents has interrupted that normal process.)

Anyway, the discussion today was about the value of home RAID systems, whether they are worthwhile and which RAID configurations are most practical/productive.  As mentioned, there were a number of opinions, both pro and con.  So I thought I'd bring it up here, see if there's any kind of consensus. 

So, the question is whether RAID is really practical for a home system - bear in mind that all of these guys (well, one (1) lady) are coders to some [varying] degree, so some form of backup/recovery system is important - and if so, what RAID version would be most viable?  (If it helps, three (3) of us have RAID setups, three (3) of us do not.  As well, the young lady is a C/++/# coder, three (3) of us are PHP, one (1) is ASP (Web), and one (1) is an ex-CoffeeCup employee who didn't want to leave when CoffeCup moved, don't know his disciplines.)

flamerz:
install a ssd, and forgot about raid.

you can mirror your hard disk to and usb in a couple of minutes.

 8)

Carol Haynes:
Forget about RAID on home systems. Waste of time and resources.

Horrendous problems with RAID 0 if you get a bad drive so you need to include another drive to make it more robust.

All for what? About a 15% speed increase (it should be 100% speed increase but that is pie in the sky on home systems).

Flamerz is right you will notice a much bigger improvement with SSD.

barney:
Sorry, but I just cannot buy the SSD vs. HDD argument on any level.  SSD is about speed, but there are shortfalls there, as well as with HDD.  They both are storage media, nothing more, nothing less.  That is not relevant to the question at hand.  Hey, you could build a RAID with SSDs as well as HDDs, ya know?  This is not a question of speed so much as a question of reliability and recoverability.  Well, OK, size enters into the equation as well, I suppose, as does cost.

The question has more to do with reliability than efficiency.  Cloud storage enters into the equation, but then the question of trustworthiness and connectivity arises.  I guess the basic question has to do more with convenience - is a reasonably good backup better than a recoverable RAID system (which would also include some kind of backup).  Time factor would be a relevant, as well as reliability.  What would provide the fastest recovery?  The most reliable recovery?

I know RAID in the home is a hot-button issue (spellcheck wanted to make that headbutting  :P), but I can see benefits, as well as detriments.  That's why we had the discussion in the first place  ;).

JavaJones:
A reasonably good backup is better than RAID because RAID only provides 1 potential advantage, and then only when it's working well: speed of "recovery". In *theory* you can quickly and "seamlessly" recover from loss of a single drive in a RAID array by simply replacing the drive that goes bad, and you don't lose any data. With most RAID solutions there is "rebuild" time during which there will be "degraded" performance, but at least your data is there. The problems with those are several.

First of all, the chances of 1 drive in your array failing go up the more drives you have. So even though adding more drives theoretically gives you more redundancy of that data, it also raises the chances that any one component in your redundant array will experience some kind of problem. Basically, it adds complexity, and that's generally not a good thing for "home" use. Managing RAID, while simpler than it used to be, also requires more technical savvy than simple backup, again it's complexity.

Second, in order to best handle a RAID drive failure, you should keep a spare drive around to swap in. This adds to cost of the solution. Cost and complexity are both factors that tend to count more negatively in a home environment than an enterprise one, and are major reasons why RAID is generally not advisable for home use, but may be perfectly useful for business use - businesses have a higher need for consistent uptime and are willing to bear the cost to maintain that. Uptime requirements in the home are generally much less significant and of lower priority.

Third, not all RAID failure is of the expected or easy to handle variety. What if it's not your drives but your RAID controller that fails? Well, if you've done it properly with hardware RAID, you need a new RAID controller which may not be cheap, probably as much or more than replacing a hard drive, and you aren't likely to be keeping one around as a spare like you would with the drive. Also, better make sure it's the exact same controller model or it might not recognize the existing RAID array.

In the end, you need a backup of the RAID anyway, and the only thing the RAID gets you that backup doesn't is theoretical speed of recovery. But that's only if you're willing to spend the money to do it right and have a spare drive around. So you have to ask yourself, is recovering my data super quickly really that important?

The other thing is the data recovery problem is potentially easily solved with a regular backup system, assuming we're talking about simple drive failure scenarios. You just setup a frequent sync to a second drive in the system (not a RAID1, although that could be done, but is generally overkill), then if your main data drive fails, you just switch over to the 2nd. Problem solved. Or, in my case, I backup to an external drive connected by USB3, I get internal-like speeds but the unit is portable, so A: it has its own power supply and may not fry even if my computer does (e.g. my PSU does in my tower), and B: if my tower does die, I can just plug my backup drive into another computer and have my data available immediately. RAID doesn't accomplish any of that.

Bottom line, RAID adds expense and complexity that is rarely justified in a home environment. I speak from some amount of experience here, I had an external RAID unit holding a ton of my data and it died on me and I had to pay a bunch of money for data recovery. RAID is not backup, and it also doesn't always accomplish the "quick recovery and graceful failure" it promises, either.

- Oshyan

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