Inexpensive RAID controller card?

[mustardman24]

Hi I was wondering if anyone knew of a consumer RAID controller card that was pretty decent and relatively inexpensive. I am planning on putting 2 seagate 160GB SATA drives in raid 0 (if that is the fast one, I'm kind of a RAID noob haha)LINK and I am wondering what would be the best for that combo of HDDs

 

[Guest]

http://www.newegg.com/Product/Product.asp?Item=N82E16816115011

You're really wasting you time with AID-0. You won't see much speed gain and you'll double the chance of hard drive failure.

Grumpy

 

[zenmaster]

Just use what you comes on your MB.
RAID-0 does not have high process overhead.

RAID-0 is really not worth the risk.

Put your Game files on one HDD and your Swap File on the other.
This may help maximize game performance.

 

[mkaibear]

>pretty decent and relatively inexpensive

ERROR! DOES NOT COMPUTE!

seriously, you don't get "pretty decent" and "relatively inexpensive". Pick one

I'd agree with the other comments - don't bother with RAID 0. Or if you *must*, use what's on your motherboard. Software RAID 0 is pretty much as fast as "hardware" RAID 0, as well - you might just try using Windows to RAID them.

 

[chunkymonster]

Also check out the Highpoint 2310. It adds RAID5, if you are worried about losing data.

Please note that RAID0 carries the same failure risk as having all your data on 1 drive. So, whether you're OS or data is on 1 hard drive or in a RAID0 array, if the drive craps out, you've lost the data either way. And, RAID0 give you anywhere from a 10-20% increase in read/write performance. Also, if data loss or drive failure is a concern, perform regular back-ups and ghost your machine every so often.

 

[mkaibear]

>RAID0 carries the same failure risk as having all your data on 1 drive.

No, it really doesn't. It has twice the failure risk of having all your data on 1 drive.

It also has an increased latency over a single disk, which for most users outweighs the additional sequential transfer rate.

 

[jt001]

You guys are all generalizing terribly, he never even mentioned how he was using it so how would you know wether he would benefit from it or not?

But like everyone else said for RAID-0 pretty much anything will do the trick, there's no parity calculation involved.

 

[chunkymonster]

>RAID0 carries the same failure risk as having all your data on 1 drive.

No, it really doesn't. It has twice the failure risk of having all your data on 1 drive.

It also has an increased latency over a single disk, which for most users outweighs the additional sequential transfer rate.

I know what you're getting at, 2 drives = twice the failure risk due to having an additional piece of hardware in the equation. But follow the logic, whether a single drive or a 2 disk RAID0 array, it doesn't change the fact that you only need one drive to fail to lose all your stuff. Therefore, 2 drive RAID0 array carries the same failure risk as a single drive. Not for nothing, I'm currently running and have run RAID0 for my OS in a number of rigs over the years without an array failure. Actually I have only ever had two drives die on me in the past 10 years; a 13GB WD and a 30GB IBM Deskstar.

I think I just jinxed myself.

 

[SomeJoe7777]

But follow the logic, whether a single drive or a 2 disk RAID0 array, it doesn't change the fact that you only need one drive to fail to lose all your stuff.

That is true. Any single drive failure, whether in a single drive configuration or a RAID configuration, loses all data.

Therefore, 2 drive RAID0 array carries the same failure risk as a single drive.

Not at all. It carries twice the risk.

Here's an equivalent example:

Bottom of the 9th, 2 outs, bases loaded, pitching team is ahead 5-4. .300 hitter coming to the plate.

If he only gets one at-bat, the likely chance of the batting team getting a hit and winning the game is 30% (he's a .300 hitter).

If we were to break the rules and let him get two at-bats, the likely chance of the batting team getting a hit and winning the game is 51% (1.000 - 0.700*0.700).

This is why RAID 0 is more risky to your data. You are using two drives, each of which carries a failure rate. Their combined chance of failure is higher than if you just had one drive. (Or, put another way in relation to the baseball analogy, the hard drive failure gremlin is getting two at-bats to ruin your data.) And since you lose all data if either drive fails, the overall chance of data loss is higher than that of a single drive (double, in fact).

 

[chunkymonster]

But follow the logic, whether a single drive or a 2 disk RAID0 array, it doesn't change the fact that you only need one drive to fail to lose all your stuff.

That is true. Any single drive failure, whether in a single drive configuration or a RAID configuration, loses all data.

You can analogize anyway you want, but this is all that really matters to the average everyday computer user who wants to know if RAID0 is more or less safe than a single drive.

 

[mkaibear]

>You can analogize anyway you want, but this is all that really matters to the average everyday computer user who wants to know if RAID0 is more or less safe than a single drive.

And hence RAID 0 is less safe than a single drive. Twice as unsafe! I don't get how this is hard for you to understand!

If the failure of any one drive will lose all data, and you've got two of them, you've got twice the chance that one drive will fail, and hence twice the chance that you will lose all data!

 

[zenmaster]

Yup. At least twice as likely to have a catastrophic failure.

Add to that the added possibility of a software/driver failure that could toast the raid set.

 

[chunkymonster]

[quote="mkaibearIf the failure of any one drive will lose all data, and you've got two of them, you've got twice the chance that one drive will fail, and hence twice the chance that you will lose all data![/quote]

Ok then, would you say that if you have a dual core proc that you've got twice the chance of cpu failure?

 

[mkaibear]

It depends on how you define CPU. But yes, you're correct. If you have a dual-core processor you have twice the chance that a transistor in one of the CPUs will fail than if you have a single-core processor. Mainly because you've got twice the number of transistors!

If you've got two CPUs on a board you've got exactly twice the chance of CPU failure.

If you've got two graphics cards, you've got exactly twice the chance of one of them failing.

If you've got two RAM sticks you've got exactly twice the chance of one of them failing.

If you've got two hard drives not in a RAID 0 array you've got exactly twice the chance of one of them failing. Of course in that case you'll not lose *all* the data, just the data on the failed drive.

 

[zenmaster]

And if a CPU, DIMM, Graphics Card, Sound Card, etc... go, then you pop in a new one and are set.

If you lose a HDD, then you lose DATA.
Popping in a new HDD is not going to help you like the other components.

At best it's going to mean many hours of reinstalling Windows and all of your software.......assuming you can find all of your disks.

Are HDD generally reliable?
Absolutely!

If you wanted, you could cut the seatbelts out of your car.
This would reduce weight and thus increase gas mileage and pickup.
Mind you it would not be significant, but it would help nonetheless.

I've never been in a car accident so I guess it's the thing to do?

 

[deweycd]

Ok, there is one thing about all this that is bothering me.

If you have a hard drive, say Drive A, and its mean time to fail is 10 years. And you decide that you want to buy another hard drive for Raid0, say Drive B and it's mean time to fail is also 10 years. (Note: I do not have particular data on common mean times to fail so 10 years is just an educated guess.)

It is true that you increase your chances of failure. But your mean time to fail is still going to be 10 years, your not going to have a mean time to fail decrease to 5 years just becasue you added a second hard drive. You do have the chance that Drive A will fail ahead of schedule, and the same goes for Drive B. It is this probabliliy that can happen, and if you only have one drive, that drive could fail ahead of time. When you have two, you double that chance that you have a faulty drive that will fail before the 10 years. The probability that you won't make it 10 years increases, but it still going to be fairly low.

As will all hard drives, you are risking your information if you do not back-up your data. It is best to have a means of securing your information in the chance that you have a failure. This goes for both single drive systems, and Raid0 systems.

 

[zenmaster]

But if you have two HDD with the MTF of 10 years, the MTF for RAID-0 will be 5 years.

MTF does not mean the drive will normally fail after 10-years.

If you have 10 Drives and run them for 1-year, then 1 will fail after a year.

If you have 20 Drives, then 1 will fail every 6months.
-------------------------------------------------------------------------------------
Lets use traditional filament light bulbs as an example.

The manufacturer 1st tests all of the light bulbs as part of quality control.
After they all pass, he tests 10,000 lightbulbs for 10 hours each. Only one fails during that 10 hour peiod. The result is a MTF of 100,000 hours.
This does not mean you can run a light-bulb for 100,000hrs until you expect it to fail.

HDD testing is much the same.
They validate the HDDs are good.
They test a large number for a short time to create a MTF.
It does not mean that 1 HDD will last the huge number of hours.

 

[chunkymonster]

It depends on how you define CPU. But yes, you're correct. If you have a dual-core processor you have twice the chance that a transistor in one of the CPUs will fail than if you have a single-core processor. Mainly because you've got twice the number of transistors!

If you've got two CPUs on a board you've got exactly twice the chance of CPU failure.

If you've got two graphics cards, you've got exactly twice the chance of one of them failing.

If you've got two RAM sticks you've got exactly twice the chance of one of them failing.

If you've got two hard drives not in a RAID 0 array you've got exactly twice the chance of one of them failing. Of course in that case you'll not lose *all* the data, just the data on the failed drive.

I'm not questioning that statistically the more hardware the greater the chance of failure. I'm very simply stating that data stored on a RAID0 array is no more or less "safe" than the same data stored on a single drive. You may have twice the opportunity of failure with a RAID0 array, but whether a single drive or RAID0, it doesn't change the fact that only one drive needs to fail.

 

[chunkymonster]

But if you have two HDD with the MTF of 10 years, the MTF for RAID-0 will be 5 years.

Just because you have two drives, it doesn't magically change the MFT of the drives to be half. The MFT of a single unit does not change just because you pair it with another unit.

That's like saying if you have tires on your car with a wear out of 50K miles and because you have 4 tires, that the wear out is now 12,500 miles. It doesn't work that way.

Statistically, the chances of drive (or flat tires) failure is increased, but in real life, the MFT is still 10 years and the tire wear out is still 50K miles.

 

[SomeJoe7777]

Just because you have two drives, it doesn't magically change the MFT of the drives to be half. The MFT of a single unit does not change just because you pair it with another unit.

That's like saying if you have tires on your car with a wear out of 50K miles and because you have 4 tires, that the wear out is now 12,500 miles. It doesn't work that way.

Statistically, the chances of drive (or flat tires) failure is increased, but in real life, the MFT is still 10 years and the tire wear out is still 50K miles.

You're correct in a way.

Pairing drives in a RAID-0 does not increase the chance of each hard drive failing. If the MTBF of each HD is 5 years, then the MTBF of each hard drive is still 5 years when paired in a RAID-0.

BUT ...

The critical thing about a RAID-0 is that data is spread across both hard drives with no redundancy, and therefore the data is now dependent on both hard drives operating. So, while the risk of hard drive failure (for each individual drive) hasn't changed, the risk of data loss has gone up.

Another example: Coin flips.

If I flip a coin, there is a 50% chance that the result is heads and a 50% chance that it's tails. This is true of each individual coin flip, no matter what.

If I have already flipped a coin 9 times and got 9 tails results in a row, what is the chance that I will get tails on the 10th coin flip? Still 50%, because that coin flip is independent of the rest. The fact that previous flips resulted in an improbable combination doesn't influence the next coin flip.

But if I ask a different question, that is what are the chances that I flip a coin 10 times and get 10 tails in a row? The chance is 0.097% (1 out of 1024). This is because by asking the question this way, the coin flips are dependent on each other to create my desired situation. ALL of the flips have to be tails, in a row.

Let's apply the math to the RAID-0:

Typical hard drive has an AAFR (average annual failure rate) of 1.5%. This means that 1.5% of the hard drives of that model will fail in a 1 year operating time frame. Let's assume I use 2 of these drives to create a RAID-0 and operate it for 1 year. What is the chance of data loss due to hard drive failure?

There are 4 situations that can happen in that year:

1. No drives fail.
2. Drive A fails.
3. Drive B fails.
4. Both drives fail.

Let's compute the chances of each situation.

Situation 2 and 3 are easy. The chance of each of those situations happening is 1.5%. 1 drive failure = the manufacturer's stated AAFR.

Situation 4 is extremely unlikely, but possible. The probability of failure is 1.5% * 1.5% = 0.0225 %.

For situation 1, we simply need to subtract all the other situations from 100%:

100% - 1.5% - 1.5% - 0.0225% = 96.9775 %.

So, let's summarize:

[code:1:6db61691d8]
Situation Data Loss? Probability
========= ========== ===========
No drives fail No 96.9775 %
Drive A fails Yes 1.5000 %
Drive B fails Yes 1.5000 %
Both drives fail Yes 0.0225 %

Total probability of data loss: 3.0225 %
[/code:1:6db61691d8]

As you can see, even though each hard drives AAFR (or MTBF) hasn't changed, the probability of data loss in the RAID-0 (3.0225%) is approximately double that of the probability of data loss on a single drive (1.5%). This is because the data is dependent on both drives being operational.

 

[mkaibear]

mate, you need to grasp the difference between "Mean time before failure" and "chance of failure". They are entirely unrelated things.

The odd thing is that you seem to grasp the basic principle;

>I'm not questioning that statistically the more hardware the greater the chance of failure.

If you have a greater chance of failure of (one of your two) drives, you have a greater chance of failure for your whole array. Surely you can see that!

>You may have twice the opportunity of failure with a RAID0 array

You do!

>but whether a single drive or RAID0 it doesn't change the fact that only one drive needs to fail

This is correct!

You've just failed to grasp that if there's twice the opportunity of failure that makes a RAID 0 array half as reliable as a single drive!