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I want to RAID 5...what do I need to know? is it worth it? newbie here

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July 1, 2008 7:30:42 PM

Well I want to use RAID 5 with my new 2k computer build as I heard it is the best RAID compared to the others. With RAID 5 you get both the speed and reliability. In Raid 0 you get the speed but you can lose data quickly. In Raid 1, you gain the reliability but you lose half your space(and lose speed i think?).

I was thinking about putting 3 of these wd 640gb hardrives together in raid 5. http://www.newegg.com/Product/Product.aspx?Item=N82E16822136218

But I heard you need a controller(wtf?) to use raid 5...is that true?

What else do I need to know?

I also read somewhere that raid 5 isn't really praticial for consumers and if it would be better to use Raid 0+1 or something like that.

Anyone know raid here? I need help lol. I thought most motherboards come raid equipped? and if it matters i am thinking about doing this mobo http://www.newegg.com/Product/Product.aspx?Item=N82E16813136042

More about : raid worth newbie

July 1, 2008 7:37:39 PM

You can use a on board RAID controller, but which board is it? Thats the DFI search page on Newegg.
July 1, 2008 7:42:43 PM

there we go fixed.
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July 1, 2008 7:52:33 PM

Why do you want RAID? What are you hoping to gain with RAID? Yes RAID 5 will offer more throughput than a single drive but will have worse access times for instance. RAID 5 is mostly used for data redundancy so the failure of 1 drive will wipe out your data. If this is just a desktop PC you might want to do something different even if you do store valuable data on this system.

In my system I use a single drive to boot and load apps, and I also have a RAID 5 array for my important data. I also have a server with much more space on it but thats another story.
July 1, 2008 7:55:48 PM

If this is for a personal computer, I would just ditch the raid setup, and get one Velociraptor and one huge 7200 rpm sata drive.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Put the operating system and programs on the velociraptor hard drive, and throw files such as pictures and music on the other hard drive. Less complicated and easier to manage in my opinion.

July 1, 2008 8:02:24 PM

Like rozar mentioned, you need to know precisely this:

Why you want RAID 5, or anything for that matter.

Is it just because you heard that it's "teh shiznit"?! In that case, google RAID 5, read up on it, understand what it gives you, and ask yourself if you need it. Also would be good to google pros / cons of it, or some such stuff.

Read up on why it exists and where it is most used.

And I think you will answer your own question.

I keep saying this to people like you - it's probably not a good idea to get technology you don't understand. Educate yourself first / get the technology second.

Edit:

Here's the thing, in case I didn't make myself clear. I'm not slamming you.

But any system planning / design should start at the problem, and end at the solution.

As in - figure out what you need. Do you need storage? Do you need fast storage? Do you need large storage? Do you need redundant storage? Do you need storage back up? What use pattern do you anticipate?

The answers to these questions will determine the solution. There are various products out there designed to address these various needs, it's a matter of matching the best one for your specific need.
July 1, 2008 8:06:09 PM

unless you need uninterrupted protection from hardware failure, then you really don't need to go with raid. just go with single drives, and a good backup. period.
July 1, 2008 8:15:15 PM

That DFI board will handle RAID 5. But what the others have said is pretty much true.

I use a raid 5 setup with 4 500 gig Seagates, in my file server/storage box. I store stuff here I do not want to lose, documents, movies, pics, DVD and CD images, that kind of stuff. I also keep a spare HD on hand in case I lose a HD in my array and need to pop in a spare and then I replace my spare immediately so I am ready in case it happens again.

My main PC uses a single 250 gig HD. However my next PC will probably use 2 250 gig Seagates in RAID 0 for a nice speed increase. RAID 0 is fast, but if you lose a HD your boned, thats why all the important stuff goes on the server.
July 1, 2008 9:24:57 PM

Yeah like I said Im a noob and not sure if I fully understand raid 5. From what I understand, I want RAID 5 because you can redundancy while retaining disk space(maybe a slight boost in performance? than a performance of a regular hardrive; not sure about this though)

Lets look at RAID 0. RAID 0 splits data accross 2 disks significantly increasing the performance of the hardrives rather than having them as separate drives. However, the downside to this, is that you get NO data redundnacy.

Now lets look at RAID 1. RAID 1 takes the data and makes a carbon copy by mirroring the data. While this is good because you get the reliability warranty, you lose half the disk space. It is also costly if you want reliability and want the disk space.

Now lets look at RAID 5. RAID 5 uses 3 or more hardrives and distributes parity data accross all of the hardrives. This way you can lose any hardrive and still have data redundancy. Because contrasing from RAID 1, you seem to get MUCH MORE space. It seems to be a much more cost effieicent way of having that reliable redundancy. You also get the performance of the RAID 0 as well. The read performance of RAID 5 almost matches RAID 0. It is much more cost effieceint that RAID 1 as you only lost like 25% rather than 50% of the data.

So basically RAID 5 is the best of both worlds right? RAID 5 combines the peformance of RAID 0 while retaining the redundancy of RAID 1?

You see this is the reason why I want RAID 5. In this day and age of computers, hardrives die all the time. I don't want to be constantly worrying about backing up data because I won't know when a hardrive will die. I would rather not have to worry about that. With RAID 5, as long as 2 drives don't die at the same time(extremely unlikely), I will have 99% redundacy and never have to resort to backup methods.

Sorry for not being exactly clear in my first post...but from what I understand(although I may be wrong on my research) this is what I want. What else do I need to know. Is my information correct?

Without RAID 5 (or RAID 1 I guess) you always have a chance of losing your data, and I never want that to happen ever again. I've had bad experiences with that.

Anyhow, thanks!
a c 179 G Storage
July 1, 2008 9:40:16 PM

As a guess, if you need to ask the question, you don't need raid.

There is generally no real world(vs. synthetic transfer rate benchmarks) performance advantage to raid of any kind.
Go to www.storagereview.com at this link: http://faq.storagereview.com/tiki-index.php?page=Single...
There are some specific applications that will benefit, but
gaming is not one of them. Even if you have an application which reads one input file sequentially, and writes
it out, you will perform about as well by putting the input on one drive, and the output on the other.

The value of raid-1 for protecting data is that you can recover from a hard drive failure quickly.
It is for servers that can't afford any down time.
Recovery from a hard drive failure is just moments.
Fortunately hard drives do not fail often.
Raid-1 does not protect you from other types of losses such as viruses,
software errors, operator error, or fire...etc.
For that, you need EXTERNAL backup.
If you have external backup, and can afford some recovery time, then you don't need raid-1.
July 1, 2008 9:48:10 PM

"What is a z-j?"

"If you have to ask, big man, you can't afford it..."

What geofelt said.

PS. Google is a powerful tool. Wikipedia - or wherever else you got the definitions from - not so much. It's even incorrect at times...
July 1, 2008 10:25:44 PM

I don't understand why people are so damn negative about raid, I'm thinking about getting myself raid5 array for my next build later this summer. The reasons are pretty much the same as moomoopro's, extra speed and data redundancy without too much wasted space.
And I was eyeing the exact same HDDs as well. :D  Those are 2 platter drives and are pretty fast just by themselves, put 3 or 4 of them in RAID5 and you got yourself a winner. and not too expensive.

but yeah, some mobo chipsets will usually support raid levels 1, 0, 1+0 and 5. Depends on the southbrigde, intels ICH9R where R stands for raid support, can handle them nicely.
You'll get better options and slightly better performance with dedicated raid controller PCI(-e) cards though

according to wikipedia you'll get nearly the same read performance with raid5 as in raid0 array with same number of drives, write performance isn't as good though. Available size is (N-1)*Smin, where N is the number of drives in the array and Smin is the size of the smallest drive.
July 1, 2008 10:35:02 PM

If you can afford it, do it. If you store vast amounts of data (specifically media servers) then its really your only option. I’m currently blowing out a 1.5 TB raid 1 and I need redundancy so I’m looking at 4 x 750 gig sata drives for raid 5 (2.1ish TB in the end). I even tried a 1 TB WD External USB drive for backups but it gets blown out. Its a completely viable option if you want *more* data protection and money isn’t much of an issue. There’s good reasons why servers use raid, in the past 15 years I can’t tell you the number of times I have had my career saved by raid when a drive pops. Not one disaster yet! But it you are just talking about less then 500 gigs of data, just buy a 500 gig drive and a 500gig USB drive that you connect just to back up the HD on occasion.

a c 122 G Storage
July 1, 2008 11:57:44 PM

I don't really "get" RAID in a PC anymore. What good is having your data backed up on a 2nd drive if something happens to your PC ? You can't access your data if applying the latest service pack fudged your box. RAID on an NAS is another story. If my machine goes south for whatever reason, I can access the NAS from any other box on the network. In an NAS, fewer parts means fewer things to go wrong.

RAID also has some sophistication that, if you are asking the questions you are, it might not be a good idea. Infrant's (now Netgear) RAID-X technology is much simpler from an administration standpoint. A drive fails, you pop in a new one and it auto rebuilds and doesn't care if the replacement is the same size.

I used to build SCSI based RAID boxes but now I just build single drive systems with fast drives and store all office and personal data files on our 9 box SOHO network on an Infrant (Netgear) NV+. Of course the NAS is in turn backed up and, short of a fire or terrorist attack, I can recover any file in seconds. Recovery from a fire would take me an hour or so.
July 2, 2008 2:51:59 AM

Kari said:
I don't understand why people are so damn negative about raid


That's pretty obvious.

Please stop quoting wikipedia as a reliable source. At one point it said that the population of African Elephants has tripled in the recent past, in the end.

And read some reputable sources, such as the storagereview site referenced above. Maybe then you'd understand why the idea of software (onboard) RAID5 is fairly ridiculous, particularly on the desktop.
July 2, 2008 6:13:10 AM

ruski, please stop telling me to search and instead help me. You seem to know a lot but you are not giving me information when I am providing enough information. You say search google, well guess what...wikipedia have the top 2 results. Whether or not you have had bad experiences with wikipedia, you have to admit, most of the information present(at least on the raid article is correct). So I don't really understand why you are discrediting it. Have you even read what wikipedia has to say? It pretty much matches the information found on "reliable sites" such as storagereview. Although wikipedia may be wrong on some accounts, can you please point out what is information is truly incorrect? It would help me out tons. *Note* I am not being sarcastic, I am serious. It would actually help me out and I'm sure others. Instead of searching aimlessly, you can just tell us!

russki said:

And read some reputable sources, such as the storagereview site referenced above. Maybe then you'd understand why the idea of software (onboard) RAID5 is fairly ridiculous, particularly on the desktop.


Please tell me WHY exactly raid 5 is impractical on a desktop setup! I have enough bays and enough hardrives to do so, why should I not?

JackNaylorPE said:
I don't really "get" RAID in a PC anymore. What good is having your data backed up on a 2nd drive if something happens to your PC ? You can't access your data if applying the latest service pack fudged your box. RAID on an NAS is another story. If my machine goes south for whatever reason, I can access the NAS from any other box on the network. In an NAS, fewer parts means fewer things to go wrong.


jack, This is why you partition your hardrives. If you make a partition for only your OS and you mess up your system by installing the latest service pack, nothing will to your other data. Only that partition which contains your OS will be corrupted.

JackNaylorPE said:

RAID also has some sophistication that, if you are asking the questions you are, it might not be a good idea. Infrant's (now Netgear) RAID-X technology is much simpler from an administration standpoint. A drive fails, you pop in a new one and it auto rebuilds and doesn't care if the replacement is the same size.


Isn't that what RAID 5 does? 1 hardrive dies, you just have to pop in another one and it will rebuild automatically since it has parity information on all drives not just 1. What is so advantageous of RAID-X technology?

The ONLY downside I can see with RAID 5 is the write performance is hindered.

Special Considerations: Due to the amount of parity calculating required, software RAID 5 can seriously slow down a system. Performance will depend to some extent upon the stripe size chosen. said:
"Special Considerations: Due to the amount of parity calculating required, software RAID 5 can seriously slow down a system. Performance will depend to some extent upon the stripe size chosen."


How much slow down will you get from using software RAID 5? Is it really that significant? Any benchmarks or tests on this?

What kind of stripe size is recommended. Also, does anyone know how much slow down a system will experience. Anyone have any percentages or benchmarks? Also when? Just when saving files, installing or what?

Recommended Uses: [b]RAID 5 is seen by many as the ideal combination of good performance, good fault tolerance and high capacity and storage efficiency.[/b] It is best suited for transaction processing and is often used for "general purpose" service, as well as for relational database applications, enterprise resource planning and other business systems. For write-intensive applications, RAID 1 or RAID 1+0 are probably better choices (albeit higher in terms of hardware cost), as the performance of RAID 5 will begin to substantially decrease in a write-heavy environment. said:
"Recommended Uses: RAID 5 is seen by many as the ideal combination of good performance, good fault tolerance and high capacity and storage efficiency. It is best suited for transaction processing and is often used for "general purpose" service, as well as for relational database applications, enterprise resource planning and other business systems. For write-intensive applications, RAID 1 or RAID 1+0 are probably better choices (albeit higher in terms of hardware cost), as the performance of RAID 5 will begin to substantially decrease in a write-heavy environment."


This is exactly what I want. russki, do YOU suggest I use RAID 5? Or are those other various products that are better designed to fit my needs?

Also what are some examples of write-intensive applications? Is the slowdown really that noticable? Or is it more of in a server environment that it is noticeable?

And the raid controller on my motherboard, is that is a hardware controller? Its just not a dedicated pci-e raid controller? Will it be good enough? Or would you guy recommend a dedicated pci-e raid controller? Will there really be a significant difference between a dedicated one than one from a motherboard? Is there another motherboard that comes stock with a better controller???

Thanks!
a b G Storage
July 2, 2008 6:52:47 AM

moomoopro said:
ruski, please stop telling me to search and instead help me. You seem to know a lot but you are not giving me information when I am providing enough information. You say search google, well guess what...wikipedia have the top 2 results. Whether or not you have had bad experiences with wikipedia, you have to admit, most of the information present(at least on the raid article is correct). So I don't really understand why you are discrediting it. Have you even read what wikipedia has to say? It pretty much matches the information found on "reliable sites" such as storagereview. Although wikipedia may be wrong on some accounts, can you please point out what is information is truly incorrect? It would help me out tons. *Note* I am not being sarcastic, I am serious. It would actually help me out and I'm sure others. Instead of searching aimlessly, you can just tell us!

I haven't checked Wiki lately, but it had perfectly accurate RAID info as of around 6 months ago (last time I checked). If I have a little time, I'll look over the wiki RAID article later and see if I can spot any problems right now, but on the whole, for factual information like this, I have found wikipedia to be quite reliable.

moomoopro said:

Please tell me WHY exactly raid 5 is impractical on a desktop setup! I have enough bays and enough hardrives to do so, why should I not?

RAID 5 without a dedicated RAID card is somewhat slow on writes, especially small writes. It flies on reads, and does have a benefit in capacity and redundancy, but the write performance suffers due to the parity calculations. This is especially true when writing files smaller than the stripe size, as in this case, it has to write the new file, read the rest of the stripe, do the parity calculations once it has the full (new) data in the stripe, and then write the parity sector, while in RAID 0 or 1, it simply has to write, not do any reads or calculations. If some speed loss on writes is acceptable to you to gain more capacity and read speed than RAID 1 while having more redundancy than RAID 0, then RAID 5 could be right for you.


moomoopro said:

jack, This is why you partition your hardrives. If you make a partition for only your OS and you mess up your system by installing the latest service pack, nothing will to your other data. Only that partition which contains your OS will be corrupted.



Isn't that what RAID 5 does? 1 hardrive dies, you just have to pop in another one and it will rebuild automatically since it has parity information on all drives not just 1. What is so advantageous of RAID-X technology?

Well, RAID 5 does require a drive of the same size as the one that failed (or, more accurately, it can use a larger drive, but will only utilize as much space on any one drive as the smallest drive). If this so called RAID-X can use varying size drives, and fully utilize all the space, that is a benefit.


moomoopro said:

The ONLY downside I can see with RAID 5 is the write performance is hindered.



How much slow down will you get from using software RAID 5? Is it really that significant? Any benchmarks or tests on this?

Read performance is almost unhindered as compared to a full hardware implementation, with the exception of high queue depth I/O, but write performance will be significantly degraded compared to a full hardware operation, especially with small random writes.

moomoopro said:

What kind of stripe size is recommended. Also, does anyone know how much slow down a system will experience. Anyone have any percentages or benchmarks? Also when? Just when saving files, installing or what?



This is exactly what I want. russki, do YOU suggest I use RAID 5? Or are those other various products that are better designed to fit my needs?

Also what are some examples of write-intensive applications? Is the slowdown really that noticable? Or is it more of in a server environment that it is noticeable?

And the raid controller on my motherboard, is that is a hardware controller? Its just not a dedicated pci-e raid controller? Will it be good enough? Or would you guy recommend a dedicated pci-e raid controller? Will there really be a significant difference between a dedicated one than one from a motherboard? Is there another motherboard that comes stock with a better controller???

Thanks!

I don't know what the ideal stripe size is - I tend to go with the default. As for the RAID controller on your motherboard, I can almost guarantee it is not a dedicated hardware controller, as those tend to go for hundreds of dollars by themselves. As for write intensive applications? I have noticed that installations are quite slow on my only RAID 5 system, and sometimes, the slowdown is noticeable. Is it horrendous? No, but in the future, I would still probably go with RAID 10 instead. You lose some capacity, but the gains in write speed would probably be worth it for me, and there is still redundancy. If you want capacity over speed though, RAID 5 is the way to go. Also, keep in mind that RAID 5 scales well, so a 4 drive array would be quite a bit faster than a 3 drive array.

EDIT: darn, this board uses different default quote tags than every other board I'm on.
July 2, 2008 7:20:38 AM

Thank you so much for the response Cjl! You were very helpful. And I agree RAID 10 seems like it would be really good. It truely combines raid 1 and raid 0 lol. And it seems like there are indeed more faults of raid 5 that are commonly overlooked ( I suggest reading http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt). Nevertheless, I still think raid 5 is still a viable option.

What setup do you have right now cjl? how many hardrives on your raid 5 system and are you using another hardrive just for your os. Because I might just do 3-4 drives in raid 5 while having a fast 10k or 15k rpm for the os and maybe some other things.

What kind of raid controller do you have? Can you recommend me one? Can most do raid 5 and raid 10? Because it would be nice if I could later switch to raid 10(if I so choose to go raid 5 right now).

and this isn't really the right place to ask but I thought i would just as you since you are pretty knowledgebale lol. On the COOLER MASTER RC-690 it says it has 5 internal 3.5"drives. It also says it it has 5 external 5.25" drives. It says on the 5.25" drives that it has a 5.25" to 3.5" converter. Does that mean I could use those as hardrive spaces. Like I potentially use like 8 hardrives? How much more power would I need and woudl I need any extra cooling lol?

Thanks man, appreciate the help!
a b G Storage
July 2, 2008 7:33:54 AM

The RAID 5 system that I have uses 4 Seagate Barracuda ES 500GB drives on an Nvidia 680i SLI board as the primary volume, and I just use the motherboard raid implementation (I didn't want to spend the money for a really good RAID card). Your motherboard should be able to do RAID 10 without a separate controller or speed loss. For RAID 5, you can do it via your board too, but because it is not a full hardware implementation, it will be slower. If you want to spend the money, Adaptec makes some very nice RAID controllers, but they will probably cost more than your motherboard did in the first place.

As for the single fast drive and big RAID volume? That is actually quite a good setup, as it removes most of the continuous load from the RAID setup, and will help hide its shortcomings (which, while they exist, are nowhere near as large as that article seems to be claiming). Keep in mind that with an integrated RAID controller on the motherboard, it will realize and alert you when it has a partial disk failure.


One thing that you won't be able to do easily is switch from a RAID 5 array to a RAID 10 array, unless you have one heck of an external hard drive and some backup software. As for the use of internal 3.5" drives in a 3.5" external bay? Not a clue - I've never tried it.
July 2, 2008 8:04:35 AM

Raid? Some years ago hard drives were not that reliable. I had 3 IBM drives go in 3 months, they were all the same type (bought at same time).
I have built/upgraded upwards of 12 desktop machines , using over 20 hard drives of various types , during the past 4 years. NONE of them have failed.Yes i am sure that is not everyone's experience. But my advice to 'myself' is - as you are 100 times more likely to lose your operating system than your hard drive - partition your drive in 2, 1 partition for operating system so you can easily wipe it( a fresh install of windows every few months is always a good idea) and 1 for user data, and just back up 'important stuff'. Then put your extra cash towards an ati 4870, or nvidia 260 gtx graphics card
July 2, 2008 1:57:57 PM

moomoopro, you misunderstood who the last reply was targeted at. It was targeted to kari, who was quoted in the message.

Everything you need was answered by geofelt, and later by cjl (who, again, misunderstood my point about wiki. So if I can save you time, don't go reading RAID wiki, I think it's pretty accurrate, if limited to the descriptive stuff). And JackNaylor (although I have had my disagreements with Jack, here he's perfectly right).

The thing about RAID is that it is fairly misunderstood by desktop users, but marketed heavily by equipment manufacturers. Because they get to sell you two harddrives when you'd be fine with one.

Bottom line is this - there's no appreciable performance benefit to RAID0 in the typical desktop scenario. As a corollary, there is no performance benefit to RAID5 in the desktop scenario. Read storagereview FAQ, or a couple of Anandtech articles.

From the redundancy perspective, it sounds like you misunderstand what redundancy requirements are vs. what backup requirements are. Even after geofelt explained it.

You need backup - most likely, and don't need any RAID. That is unless you're not telling us everything and plan to use your PC as a media workstation (in which case there's marginal benefit to RAID, but RAID0 probably makes more sense), or a server - in which case it's a totally different ballgame, and you probably need a decent controller, because software RAID5 is costly, particularly on rebuilds - so there goes your redundancy.

Oh, and there are about 20-30 posts on these very forums discussing this very thing.
July 2, 2008 3:33:31 PM

RAID 5 is mostly used in "servers". Now that’s not to say you can’t use it in a desktop but remember RAID does not equal backup. Plus in servers I always try to set up customers systems with a boot volume (or array such as RAID 1) and then have RAID 5 for the DATA. I discourage anyone from having a single RAID 5 array that is for DATA and boot, even if you use more than 1 partition.

This decision must also consider what else you use for storage or backup. Do you have another server or machine in the house to store important data on? Do you burn important stuff to DVD? If so it might be less important for you to have redundancy in a desktop system.

Also remember that ALL RAID levels you gain one or more of 3 things.
Redundancy
Speed
Volume size
All RAID levels also have a downside (I will list a few)
RAID 0 is not redundant and slows access time
RAID 1 has a high overhead and performance depends on the controller
RAID 5 slows write speeds and access time

So basically a Single drive has its advantages too and I think that is what a lot of people here are trying to tell you.

I will also go back to what I said in my first post, you need to know why you want RAID (any level). If you are not doing RAID for a specific reason then don’t do it. If it’s for redundancy then if possible don’t boot off it. Install a single fast drive like the new WD raptor to boot from and then use a RAID 1 or RAID 5 for your data.

Hope this helps
July 2, 2008 4:33:40 PM

In principle, I'd have to agree with most of what russki said here.

RAID (all levels, not just RAID 5) has one primary purpose, that is availability. This is the capability to keep the system up and operational when a hard drive fails. This is a feature that servers need, not desktops.

RAID is not backup. It is not designed nor is suitable to replace a true off-line backup. The purpose of a backup is to save your data from any destructive cause -- OS corruption, malware/virus, accidental deletion/format, or to just plain go back to an earlier version of a document. RAID cannot protect against any of these things. The only destructive force that RAID can protect against is hard drive failure.

So since RAID isn't a substitute for backup, you're going to have to put a backup plan in place anyway. That fulfills protection from hard drive failure as well as everything else, leaving RAID as an availability solution only. Since a desktop seldom needs the availability of a server, you have to ask yourself what you're installing a RAID for?

Further, there is a problem with RAID on the desktop from a reliability standpoint. Enterprise-level RAID cards, like those from 3Ware, LSI, and Adaptec are robust and reliable. Do a quick search on this forum and you'll find dozens of threads that start out with statements similar to the following:

"I was running RAID on my desktop Intel chipset, and all of a sudden the array is listed as degraded ..."
"My nVidia RAID isn't listed in my bootable devices ..."
"My RAID array won't rebuild ... it keeps saying the new drive is bad ..."

Almost all of the desktop RAID controllers seem to have reliability problems of this type. An unreliable RAID that drops out the array or won't rebuild it when a drive goes bad is useless.

About the only other theoretical thing that RAID can give you is higher data transfer rates. But the question is, is that useful for your application? There are a few applications that benefit greatly from high transfer rates (Photoshop scratch disks, DVD authoring, media file creation and video editing applications, professional audio programs like ProTools). Then there are applications that do not benefit at all from sequential transfer rate. Most people here and benchmarks by several web sites offer evidence that gaming falls into this category - i.e. maybe a few percent decrease in load times, if that.

Thus, my conclusion is that unless you have a specific application that can benefit from RAID's high sequential transfer rates, or you have a specific application that needs the availability, the risk, complexity, and cost of using RAID on the unreliable desktop RAID chipsets is too high to justify the small performance benefits.

There is one situation not mentioned here where RAID can benefit, that is where you need to store a quantity of data that is beyond currently available drive sizes, and particularly if you have no means to back up that data. For example, if you want to build a media server to store audio and movies, and need to store 3 TB of data. In this case, RAID 5 would be very worthwhile, because it gives you at least some protection against hard drive failure, and is the only way to get a volume size >1TB right now (1TB hard drives are the largest available).

However, in this case, I definitely would not use a desktop chipset controller. An Enterprise RAID card is definitely warranted here due to the reliability and need to make sure that your data isn't compromised, especially since you can't back it up.

Furthermore, Enterprise level RAID cards perform much better than desktop chipsets -- not due to the parity calculation capability, but predominantly due to the large write cache that can do delayed writes. This prevents a lot of the write-read-calculate-write cycles that cause slow RAID 5 writes on desktop chipsets.

For a typical desktop these days, I like a standard 2-drive setup. Use a very fast drive for C: (Raptor, Velociraptor, or high-end 7200 RPM drive like Seagate 7200.11 or WD Caviar Black), and then a large 7200 RPM drive for D:. Install OS and programs on C:, data on D:. Invest in Acronis True Image, Symantec Ghost, or some other imaging program, and image C: to a file on D: once a week.

For me, that makes the fastest, cheapest, and most robust desktop system. Obviously, this can be modified to suit particular applications.
July 2, 2008 4:48:56 PM

Typically you'd see RAID 5 used in conjunction with hardware that is hot-swappable. This way when a drive fails, there is no need for downtime. If you're doing RAID 5 with regular PC hardware you're losing one of the main benefits of RAID 5. I'd guess the % of home users running RAID 5 arrays is less than .001%. I just pulled that number out of my head, but I'd wager it's pretty accurate. It's just not something you see in personal computers. Performance junkies typically go the RAID 0 route and people who are overly paranoid (or too lazy to do routine backups) go the RAID 1 route.
July 2, 2008 4:58:13 PM

rodney_ws said:
I'd guess the % of home users running RAID 5 arrays is less than .001%.


With these posts popping out lately I'm just not so sure.

SomeJoe - excellent points, as always. Another thing I would add that in using onboard controllers and, say, your mobo frying when a new generation of hardware is widespread and the old no longer available - you're running a big risk of not being able to migrate your array and being stuck with [practically] unretreivable data. We've seen some of these threads started recently. And that's no drive failures, just a mobo failure (and thus the controller).
July 3, 2008 8:30:37 AM

SomeJoe7777 said:


RAID is not backup. It is not designed nor is suitable to replace a true off-line backup. The purpose of a backup is to save your data from any destructive cause -- OS corruption, malware/virus, accidental deletion/format, or to just plain go back to an earlier version of a document. RAID cannot protect against any of these things. The only destructive force that RAID can protect against is hard drive failure.

So since RAID isn't a substitute for backup, you're going to have to put a backup plan in place anyway. That fulfills protection from hard drive failure as well as everything else, leaving RAID as an availability solution only. Since a desktop seldom needs the availability of a server, you have to ask yourself what you're installing a RAID for?


Somejoe, you make some very valid points and i thank you for the insight. I guess the performance increase of RAID isn't what I really care about but rather the data redundancy. And for me, I think backing up is annoying and costly. To backup 2 tb of data would be annoying lol.

And Fortunately I do not run into any of these problems.(the past 10 years, never had anything that bad) My problems have always been hardrive failures so I guess raid is what I need to be honest.

And I definitely agree with you and can see how raid can be useless in comparison to using a server. The thing is with my case, I don't have any room/money for a server. I'm a college kid. So using RAID suits me much better.

SomeJoe7777 said:
About the only other theoretical thing that RAID can give you is higher data transfer rates. But the question is, is that useful for your application? There are a few applications that benefit greatly from high transfer rates (Photoshop scratch disks, DVD authoring, media file creation and video editing applications, professional audio programs like ProTools). Then there are applications that do not benefit at all from sequential transfer rate. Most people here and benchmarks by several web sites offer evidence that gaming falls into this category - i.e. maybe a few percent decrease in load times, if that.


I actually do all those things 0_0. So I guess RAID would be more useful than I once originally though.

SomeJoe7777 said:

There is one situation not mentioned here where RAID can benefit, that is where you need to store a quantity of data that is beyond currently available drive sizes, and particularly if you have no means to back up that data. For example, if you want to build a media server to store audio and movies, and need to store 3 TB of data. In this case, RAID 5 would be very worthwhile, because it gives you at least some protection against hard drive failure, and is the only way to get a volume size >1TB right now (1TB hard drives are the largest available).


I'm definitely going to have a setup like this.

A few questions though:
1. with external backups you gain extra security but what prevents the hardrives in the external backup to not fail? are those raid equipped as well?

2. you say that software RAID 5 is risky on rebuilds(many drives fail on software rebuilds but not hardware) and that it is really slow. Does this apply to software RAID 10 as well?

3. I am really concerned about the risks about RAID 5 contained in this article http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt even though clj said they weren't as big as the author mentioned. (located in the last 3rd of the article) such as the drive failing when rebuilding. and this:

The problem is that despite the
improved reliability of modern drives and the improved error correction
codes on most drives, and even despite the additional 8 bytes of error
correction that EMC puts on every Clariion drive disk block (if you are
lucky enough to use EMC systems), it is more than a little possible that a
drive will become flaky and begin to return garbage. This is known as
partial media failure. Now SCSI controllers reserve several hundred disk
blocks to be remapped to replace fading sectors with unused ones, but if
the drive is going these will not last very long and will run out and SCSI
does NOT report correctable errors back to the OS! Therefore you will not
know the drive is becoming unstable until it is too late and there are no
more replacement sectors and the drive begins to return garbage. [Note
that the recently popular IDE/ATA drives do not (TMK) include bad sector
remapping in their hardware so garbage is returned that much sooner.]
When a drive returns garbage, since RAID5 does not EVER check parity on
read (RAID3 & RAID4 do BTW and both perform better for databases than
RAID5 to boot) when you write the garbage sector back garbage parity will
be calculated and your RAID5 integrity is lost! Similarly if a drive
fails and one of the remaining drives is flaky the replacement will be
rebuilt with garbage also propagating the problem to two blocks instead of
just one. said:
"The problem is that despite the
improved reliability of modern drives and the improved error correction
codes on most drives, and even despite the additional 8 bytes of error
correction that EMC puts on every Clariion drive disk block (if you are
lucky enough to use EMC systems), it is more than a little possible that a
drive will become flaky and begin to return garbage. This is known as
partial media failure. Now SCSI controllers reserve several hundred disk
blocks to be remapped to replace fading sectors with unused ones, but if
the drive is going these will not last very long and will run out and SCSI
does NOT report correctable errors back to the OS! Therefore you will not
know the drive is becoming unstable until it is too late and there are no
more replacement sectors and the drive begins to return garbage. [Note
that the recently popular IDE/ATA drives do not (TMK) include bad sector
remapping in their hardware so garbage is returned that much sooner.]
When a drive returns garbage, since RAID5 does not EVER check parity on
read (RAID3 & RAID4 do BTW and both perform better for databases than
RAID5 to boot) when you write the garbage sector back garbage parity will
be calculated and your RAID5 integrity is lost! Similarly if a drive
fails and one of the remaining drives is flaky the replacement will be
rebuilt with garbage also propagating the problem to two blocks instead of
just one."


I didn't really understand what he was saying with the garbage being spit back out. How likely are these to occur even if you have a nice dedicated hardware RAID controller?

4. I am really thinking about going RAID 10 now. I know that the software RAID 5 had a bunch of faults and that using hardware is strongly recommended. Is it strongly recommended that I use a hardware RAID controller for RAID 10? or does software RAID 10 not have the same problems as RAID 5 due to its construction?

5. I plan on using 4 drives in either RAID 5 or 10. I will then be using 1 fast drive for the OS. Either a 10k or 15k. Most 10k drives are SATA so I know my mobo will support those. But what about those 15k drives? They come in Ultra320 SCSI, SCSI Ultra320 68pin, SCSI Ultra320 80pin, Serial Attached SCSI (SAS). Do most motherboards support these formats(does mine, if not recommend one?).
5a. For those formats do you need a separate controller specifically for it?

I was looking at these 2 hardrives http://www.newegg.com/Product/Product.aspx?Item=N82E168... and the http://www.newegg.com/Product/Product.aspx?Item=N82E168.... Do these 2 look good? They don't have any reviews or anything....i wonder why that is lol.

6. Can you guys recommend a good RAID controller card? This one looks quite nice and comes at a pretty decent price. http://www.newegg.com/Product/Product.aspx?Item=N82E168... Its the Adaptec 2251800-R 4-lane PCIe SATA / SAS 3405. Any comments on that or any other suggestions? Thanks
July 3, 2008 2:25:49 PM

Moomoopro you cant just ask these kinds of questions without giving us some kind of budget. Yeah the Adaptec 5 series of controllers (about the fastest right now) will make your system faster but its expensive. Really its more money than most want to spend. 15k drives are nice too but there is alot of argument about which is better 15k drives or the new raptor. Plus the 15k drives cost more, so again money comes into play.

About your theory that backup takes too long and is annoying. If you dont backup thats your choice but you have to understand that RAID is NOT NOT a backup. If you have a delayed write failure you can corrupt a RAID array and lose all data. It can happen, I have see it happen. You must use some means of backup or you will eventually regret it.

I do like you current plan booting off one volume (RAID or not) and then having data on anohter volume. This is good, and it will keep a single drive failure from taking out your array and data.


Here are a few links for you

http://www.tomshardware.com/forum/245522-32-adaptec-ser...

http://www.tomshardware.com/forum/246133-32-raid-single...

http://www.tomshardware.com/forum/forum2.php?config=tom...
July 3, 2008 3:41:12 PM

moomoopro said:

1. with external backups you gain extra security but what prevents the hardrives in the external backup to not fail? are those raid equipped as well?

2. you say that software RAID 5 is risky on rebuilds(many drives fail on software rebuilds but not hardware) and that it is really slow. Does this apply to software RAID 10 as well?

3. I am really concerned about the risks about RAID 5 contained in this article http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt even though clj said they weren't as big as the author mentioned. (located in the last 3rd of the article) such as the drive failing when rebuilding. and this:

I didn't really understand what he was saying with the garbage being spit back out. How likely are these to occur even if you have a nice dedicated hardware RAID controller?

4. I am really thinking about going RAID 10 now. I know that the software RAID 5 had a bunch of faults and that using hardware is strongly recommended. Is it strongly recommended that I use a hardware RAID controller for RAID 10? or does software RAID 10 not have the same problems as RAID 5 due to its construction?

5. I plan on using 4 drives in either RAID 5 or 10. I will then be using 1 fast drive for the OS. Either a 10k or 15k. Most 10k drives are SATA so I know my mobo will support those. But what about those 15k drives? They come in Ultra320 SCSI, SCSI Ultra320 68pin, SCSI Ultra320 80pin, Serial Attached SCSI (SAS). Do most motherboards support these formats(does mine, if not recommend one?).
5a. For those formats do you need a separate controller specifically for it?

6. Can you guys recommend a good RAID controller card? This one looks quite nice and comes at a pretty decent price. http://www.newegg.com/Product/Product.aspx?Item=N82E168... Its the Adaptec 2251800-R 4-lane PCIe SATA / SAS 3405. Any comments on that or any other suggestions? Thanks


1. Nothing prevents the backup drives (or tape, or DVD, etc.) from failing any more than the original drives can be prevented from failing. But if you have two separate, unrelated copies of data, you have reduced the chance of any single failure taking out both copies to nearly zero. If a backup drive fails and you lose your backup, you just buy another backup drive and create a new backup. You can use hard drives to back up, and RAID them if you want, or you can use some other backup method (tape works very well for large quantities of data, but is very expensive for modern high speed tape formats because the drives are not cheap).

2. No, I said that software RAID was risky on rebuilds, not software RAID 5. It's risky because of the driver problems, not because of the RAID itself. It's the implementation that's the problem with those cheapie motherboard controllers, not the theory of RAID. Yes, it applies to software RAID 10 because the same cheapie controller and driver are being used.

3. I think those risks are overstated. Yes, you can lose a 2nd drive during a rebuild and trash the array. That's why you also need a backup. This is also true of all RAID systems, even RAID 10. RAID 10, by chance, can handle the failure of multiple drives in the array as long as they're not both a part of the same mirror set, but if it does happen to be the other drive of the mirror set, then it can be lost as well. Many newer enterprise RAID controllers can now do RAID 6, which can handle any 2 drive failures.

Most enterprise RAID controllers can do periodic media patrol/media integrity scans and RAID redundancy verifications, which mitigate the possibility of a sudden, surprising drive failure. (Another feature that the cheapie motherboard RAID controllers don't have).

4. I always recommend an enterprise RAID controller for any RAID, regardless of the RAID level. The cheapies have the aforementioned reliability issues. Again, this is not at all tied to the particular RAID level (0, 1, 5, 10, 6, or otherwise). It's the robustness and reliability of the driver-hardware combination that's the issue.

5. Only one drive is a 10K SATA - that's the WD Raptor and Velociraptor series. Most 10K drives and all 15K drives are SCSI or SAS. Only a few server motherboards support SCSI or SAS on the motherboard. You would need a SCSI or SAS controller to support these drives. (If you go this route, you need to go with SAS. The older parallel SCSI is being phased out, just like PATA).

6. Enterprise level SATA RAID controllers that are known to be high-end and robust include the Adaptec series you mentioned, controllers from LSI Logic, and controllers from AMCC/3Ware. I have a personal preference for the 3Ware cards, I have used many models of them over the years and they have always worked very well. My current home media server uses a 3Ware 9650SE-16ML. The 3Ware cards also have very robust Linux support, should you wish to use them on a Linux server.

You realize, of course, that going this route with these recommendations is going to cost some money. You don't get something for nothing. Your final costs will be determined by which card you go with, which drives you go with, the RAID level you choose, the backup mechanism you choose, and the case, motherboard, OS drive/controller, etc. You can easily spend $3K-$4K on a machine of this magnitude. You will have to weigh whether your data is worth that or not.

Also, if you're going to make an array larger than 2TB on Windows, you will need to read up and become familiar with GPT disks and the DISKPART utility.
July 3, 2008 4:01:56 PM

One this that needs to be taken to heart here is Backup. Even if you only use a Single drive external USB (or eSATA/firewire) hard drive enclosure. You could put a 1TB drive in it for very low cost and use that as backup. This is a good starting point for backup and it does not take up much space, plus its portable. Also dont forget DVD you can use that too, it may be small but its can serve as backup for the most important files.

I agree with Joe on the controllers he has listed. I use LSI/Intel SAS in my system at work, I use Adaptec SAS in my home personal machine, I use 3ware SATA in my server and I also use 3ware SATA in my media center.
July 3, 2008 9:14:30 PM

moomoopro, you are highly incosistent.

Which is why I told you - why don't you figure out what you need?! As in what are you going to use your system for. Gaming? Media editing? Serving?

You say you want to go the route of RAID 10, use 15,000 RPM drives, and have volumes exceeding 1 TB. Okay. Here's the thing. The largest SCSI harddrives, I think (Joe, please correct me if I'm wrong) are 300GB. At about a cool $1,000 a pop (15,000 RPM). Which means your 4-drive 10 array is limited to 600GB, at a cost of $4,000 for the drives alone. By the way, these babies need cooling, too.

What is it that you really need / want?
July 3, 2008 10:11:16 PM

russki said:
The largest SCSI harddrives, I think (Joe, please correct me if I'm wrong) are 300GB. At about a cool $1,000 a pop (15,000 RPM).


Most of the currently-manufactured SCSI/SAS drives top out at 300GB, yes. However, Seagate's new Cheetah 15K.6 line has a 450GB model, but it's difficult to find in the retail channels right now.

There is also a Seagate Cheetah NS drive (a near-line drive, meant for disk-to-disk backup and things like that) that is 400GB, but it's 10K RPM, not 15K, and is not as fast as the regular 10K Cheetahs.
July 4, 2008 3:05:15 AM

Thanks for the info guys, much appreciated.

For a RAID controller I'm looking for 1 less than $500. I just want the best bang for my buck really. And after much thinking I don't think I will use any SAS drives and will just stick to SATA. SAS is much too expensive. I'm probably just going to get 1 of those raptors for the OS, and then stick 4 other hds in raid.

Can you guys recommend me a card? I'm getting pretty overwhelmed, there's many different kinds. I was looking at 3ware's site and they have Serial ATA RAID, SATA 2 PCI-X RAID and SATA 2 PCI extpress with RAID 6. I'm don't need SAS or PATA raid, so those are out of the question. I don't really understand the difference between those 3 that I listed above. Is SATA 2 faster, thats the only difference. Which one do I want?I want something:
Only need SATA(don't need SAS)
preferarbly less than $500
has a battery backup module(BBM)
has at least 4 slots for the hardrives
good amount of cache
and runs cool(i heard that some of the adaptec ran very hot and 1 person's card fried lol)

I was looking at this card made my 3ware and it looked really nice! 3ware 9650SE-4LPML http://www.newegg.com/Product/Product.aspx?Item=N82E168... It has 4 ports, supports SATA 2 pci-e, 256mb ddr2 cache, and it supports BBU...and its priced reasonably. Any suggestions besides this card, or is this card good?

What exactly makes a RAID card Enterprise level?

And how important is the cache? Is 128 truley enough or should I bump it up to 256?

And for right now, I'm probalby going to stay under 2tb, but barely. I'll get to 1920 gb lol. I didn't really read much, but why does it matter if I go over 2gb?

Yeah, I mean of course I'll be backing up the very important data on probably a external hardrive but I;m not going to for everything lol.

rusky, read my posts. ive said it b4...in short everything.
July 4, 2008 4:22:17 PM

The 3Ware 9650SE-4LPML is a very popular and very nice card. It is the 4-port version of the one I linked to above.

The 3 different model lines of the 3Ware cards that you mentioned differ primarily in their interface and the SATA transfer rates they support.

9500S series is PCI-X (not PCI Express aka PCIe), and will also run in a regular 32-bit PCI slot. It supports SATA 150MB/sec transfer rates only.

9550SX series is PCI-X (not PCI Express aka PCIe), but will not run in regular 32-bit PCI slots - the slot must be a real server-based PCI-X slot. It supports SATA 300MB/sec transfer rates as well as 150MB/sec.

9650SE series is PCI Express (PCIe). The interface is PCIe x4, so it must be used in a PCIe x4, PCIe x8, or PCIe x16 slot, so make sure your motherboard has one of these available. The 9650SE supports SATA 300MB/sec transfer rates, and also supports RAID 6.

9690SA series is similar to the 9650SE, but supports SAS drives as well as SATA drives.

You will need to purchase the battery backup unit separately. The proper battery backup unit that goes with the 9650SE series is the BBU-MODULE-03.

Now, I happen to be partial to 3Ware, but there are other cards in this price range that work well:

Adaptec 5405

I know some people also have used the Areca cards, but I'm not familiar with them.

I have used LSI Logic cards as well (they are the manufacturer for most of the Dell PERC cards used in their PowerEdge servers), but I have not used a retail model.

TO me an Enterprise level RAID card has the following that differentiate it from a "prosumer" or consumer RAID solution:

- Write cache - very important for doing delayed writes to RAID 5
- RAID level migration
- Online capacity expansion
- Media patrol/background scan
- Redundancy verification

If you go over 2TB, you have a whole new ball of wax to deal with. :)  The limit for the standard MBR partitioning scheme under Windows is 2TB. Going over 2TB requires a new disk format known as GPT.

All versions of Windows Server 2003 with SP1 or higher (including R2), Windows XP Pro x64, and all versions of Windows Vista can use GPT disks, which can be any size up to the current implemented limit of the NTFS file system (currently 256 TB).

The controller you're using must support >2TB arrays for that to work. (The 3Ware controllers and Adaptec controllers mentioned here do).

You can only use GPT disks on Windows Server 2003 and Windows XP x64 as data disks, not boot disks.

See the Windows and GPT FAQ for more detailed explanation.
July 7, 2008 4:28:50 PM

I second the recommendation for the 3ware 9650SE-4LP card. This is a very solid card for your setup. This card can also do "auto carving" in case you are using XP and your array size will be more than 2048GB. (4 - 750GB hard drives in RAID 5 for example is 2095GB and Windows XP would not see the volume in disk manager) It can also set a boot volume too if you wanted to take the same setup above and set a 50GB boot volume, (even though you are not booting off of it) this gives you less than 2048GB for the primary volume and XP will see it.

The Adaptec 5405 while being a good controller does run hot and needs active cooling, it also has half the cache of the other 5 series Adaptec cards. It is faster than the 3ware 9650 series though.
July 9, 2008 5:28:01 AM

thanks for the info guys much help!

i know some people may think raid is a waste and advise against it but i want it.

I will be purschasing 3ware 9650SE-4LP card along with the BBU unit...thanks again for the help. it has taught me a lot
!