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Basics of RAID
Doggie Fizzle writes "RAID has been common in business environments for ages, and is now becoming more viable and popular for personal computers. This article focuses on the the basics of RAID, and spells things out for beginners or tech veterans. From the article: 'The benefits of RAID over a single drive system far outweigh the extra consideration required during installation. Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens.'"
Anyone ever get the feeling Zonk just doesn't get the Slashdot target demo?
That's an awful lot of ads for a re-hash of well-known info. Are the editors sure this is frontpage worthy? It looks like a blatant attempt to get page views to me.
A source of information with far better content, that isn't simply an excuse to sell ads.
Wikipedia
Okay I guess it appeals to geeks and fancy computer modders and all. But really, when it comes down to it, a decent main hard-disk, a tray in the second bay for backup hard-disks, and a reasonable backup regimen that people keep up is all a "personal" computer user needs.
Personally, I have 3 backup hard-disks, one that keeps a "clean" base system that I update every 6 months or so, and 2 that I do full differential backups on every 3 days. The "clean" hard-disk is kept off-site, and a script tells me when to do the backups on the other 2. And for very very important files, I just write them on a CD on the spot.
With that, I've yet to lose a single file since I started using Linux in 93 or 94. My solution is cheap and doesn't involve fancy raiding. And I'm quite sure I overdo it, most people could do just fine with one main hard-disk, one backup hard-disk and a little discipline.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
. Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens.
:)
Because otherwise, you can tell them all about the wonders of RAID and all they'll do is just pretend to be interested while secreting thinking that you are some mad geek.
Tell them about the wonders of RAID after they've been kicked in the nuts by a drive failure, and you sure as hell would be getting their whole undivided attention.
Making the most of your effort man.. that's what it is
Online backup with Mozy, sounds like Ozzie, but more!
As a (poor) student, I find that I simply can't afford an extra hard drive! I got a 2nd hand DVD burner from a friend for £15 and backup all my really important stuff (Code for university, photos, etc) every week. All my MP3s go on another DVD along with the hard disk, and they're "backed up" on my MP3 player anyway.
As of yet I've never had a single hard disk failure... but I've not really got anything I'm bothered about losing, so RAID isn't worth it for me.
There is nothing more practical than a good abstract theory.
With RAID, you still have a single point of failure. Instead of it being your hard drive, it is now your RAID controller. So what is the advantage?
You get a new one under warranty or buy one...and your data is still there. If your drive dies and you get a new one your data's toast unless you have megabucks for Drive$aver$.
Yes.
The controller's still a point of failure. Indeed, with some RAID controllers if they go bad they corrupt data on *both* your disks, rendering both unusable.
RAID protects against hardware failure of a drive.
It does not protect against a bad controller or an OS snafu (for example, I once had the MSFT go bad on an NTFS volume, losing all data on a drive. RAID wouldn't have helped me there, either).
So if you really care about your data, you should run RAID in conjunction with an off-disk backup solution. Preferably something that is regularly refreshed and kept seperately from your computer.
-EvilMagnus
Alternatively to DVD backups, you can also sync up your data on a regular basis to an external hard drive. This doesn't protect you if your house burns down, like DVD backups kept in a safety deposit box would do, but it does help you restore lost data after it gets corrupted.
Ultimately, all these solutions require varying amounts of money, time, and effort, so you just have to decide what level of security you require and what you are willing to pay for it.
There are two types of people: Those that have lost data, and those that will.
Don't forget, though kids - RAID won't protect you from deleting your own data, or a malformed script trashing stuff.
Get your own free personal location tracker
"Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens."
Why? That's actually quite simple. Losing consciousness once due to a brick falling on the head may be all that is required to convince anyone that a helmet is right for them, but we don't see people wearing helmets, do we? Do people wear bulletproof vests? No? Why not? After all the benefits of a bulletproof vest over an ordinary vest far outweigh the extra consideration required during installation! Please, people, could we stop being such naive children thinking that our beloved industry is somehow special, that ones and zeroes have more value than humen lives? Could we please stop being so pathetic once in our lives? RAID may be a nice idea for "nerds that matter" but it is not for grandma. Period.
Karma: Positive (probably because of superiour intellect)
Ultimately, what it comes down to is that mirroring merely makes the hardware more reliable, it is not a backup technique.
The higher the technology, the sharper that two-edged sword.
I've sold Entreprise hardware / software / projects for over 13 years, and the handful of catastrophic data losses / service interruption / nightmarish server setup / stability issues my clients have had have ALWAYS been with RAID systems.
;-) I have no real-life experience with FC and the thing over ethernet yet. i'm VERY leery of my customers being used as beta-testers / guinea pigs.
...
Of course, if you're using RAID it's because you need capacity / speed / reliability, and while it seems the first two are indeed delivered, there is a HUGE reliability issue.
Back in the days when i was selling Dell's own RAID array (can't remember the name), it was well known at Dell that the controller software was buggy, they fired the programmer but still sold the stuff. And thing haven't improved since. A couple of years ago it took a Compaq high-end VAR several MONTHS to get multi-gig RAID5 setup working. My brother works for a very large company, and after months of problems, their SUN lead person admitted that SUN has issues with their RAID controllers, especiallly the replacement ones / spare parts. Remember when SETI@HOME went down for a week a couple of years ago ? SUN RAID controler problems !
My advice to clients is to avoid RAID whenever possible. Have spare servers, do very frequent backups, split your databases, have gobs of RAM... For the cost of a first-tier RAID system, you can buy a lot of other stuff, that WILL be useful in a lot more cases: fried servers, corrupted files... It's too bad the SCSI disks we use lag so much is capacity compared to ATA. I haven't done any SATA yet.
The one thing less reliable than RAID is clusters, BUT i haven't handled clusters in a while, i'm talking 5 years ago. May be the new Linux ones are better
My 10 cents
Sorry for the "AC", but since I'm naming names
My father has trusted his data (against my advice) to fakeraid chipsets on his various motherboards twice. He just got done *losing* all of his data for the second time.
Best we can tell, he had one drive go without his RAID controller warning him; then had a second drive go, killing the array. He spent weeks with a dead PC playing with all kinds of special Windows bootloaders and disk recovery tools trying to get his files back.
Fakeraid sucks because it's just a line item on the sale of a modern motherboard. The inclusion of the "RAID" functionality is borderline fradulent. REAL RAID controllers, of course, have a coprocessor and often battery backup and leave all of the storage details to themselves rather than some fly-by-night driver in the operating system.
It's no surprise that they come with virtually nothing in terms of recovery software.
The happy median, I've discovered, is Linux md. md supports many RAID levels, and according to some benchmarks will certainly outrun fakeraid in performance (which doesn't particularly surprise me). The administration tools let you simulate drive failure, monitor array health, create degraded arrays, and the documentation tells you what to do when something goes wrong.
Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens.'"
Isn't it human nature (or at least that's what it seems) to wait until something "bad" happens?
That goes for obese people, smokers and yes even computer geeks.
Why eat all the fat? I'll just burn em all!
- Wait til your 40-50 and check that cholesterol strike...
So many people smoke and get away with it so I will to right?
- Yeah wait til you get some health problem that will make you say "OH NOES!"
Why I need firefox? ActiveX hasn't screwed me.
- A week later "omfg whats all this junk, I want Firefox!"
Why Do I need RAID or even a burner? I got 3 hard drives that contains all my data!
- 8 months later, 1 hdd crashes "AH F*K ALL MY Pr0n!" and then he thinks of having a simple RAID 1 setup...
We always wait because we are lazy and cheap.
1. The average user does not need RAID.
2. The enthusiast does not need RAID.
3. RAID is not a replacement for backing up.
RAID is only good for two things: To protect against a hard drive failure when an uptime as close as possible to 100% is required; and to increase performance in the form of data throughput.
Alright, let's cover them one at a time. The average user (anyone who just buys a Dell to surf the web,) doesn't need RAID. Hard drive failures are fairly uncommon. And the to the 'average' user, 100% uptime isn't anywhere near a necessity. Also, data throughput isn't that important, either. (Besides, for most people, buying a faster hard drive is both technically better and more cost effective.)
Most enthusiasts (gamers, hardware tweakers, modders, etc,) don't need RAID. Again, hard drive failures are fairly uncommon, and your average enthusiast doesn't exactly store cures to cancer or rocket science on their drives. (No, the old MS Space Simulator doesn't count as rocket science.) Besides, most enthusiasts use RAID-0, which isn't really redundant. Which brings us to point B. The only thing RAID-0 measurably improves is sequential STR speed (Spindle-to-RAM, the speed of data going from the platter to the drive's internal cache.) And there are very few enthusiast tasks that do better from a raw higher throughput. (Even capturing video doesn't matter, as the slowest hard drive today can easily keep up with uncompressed HD!) Oooh, so your Doom3 level loads 1/2 a second faster. In single-player mode, it doesn't matter at all, and in multiplayer, the server waits for everyone to load anyway. RAID doesn't help for random seeks. A faster spindle helps for that. A better drive caching algorithm and a larger drive cache helps for that. If you have a 40GB, 5400RPM, 2MB cache drive, you'll see a tremendous improvement by going to a Raptor, or to a 15k RPM SCSI drive. You will see very negligible benefit by getting a second 40GB, 5400RPM, 2MB cache drive and putting them in a RAID-0.
Finally, the assertion that RAID prevents data loss. The only data loss it prevents is loss due to a failed hard drive. It doesn't protect against user error, viruses, or physical damage that destroys the whole computer. If your data is truly vital, you need to be backing up, even if you do use a RAID. Yes, businesses with vital information who need (as close as possible to) 100% uptime need RAID. That's it. Even then they still need backups.
Another non-functioning site was "uncertainty.microsoft.com."
The purpose of that site was not known.