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SSDS and SATA2/SATA3 Question?

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June 27, 2011 10:47:29 PM

Ok so I on my current system I have 2 OCZ Vertex SSDs in RAID 0, and on my system the speed limitation has been the limitation of SATA2's max transfer rate. So I ordered a new motherboard (P67/sata3/usb3) and a Sandy bridge i7. If the SATA2 motherboard was limiting the hard drive's transfer rate, will having a SATA3 motherboard improve performance at all when the drives arent "SATA3 drives". So my question is, if my SATA2 SSDs in RAID0 go faster than the speed of SATA2, will SATA3 allow them to go faster even though the SSDs themselves arent SATA3?

Thanks in advance for clearing up my confusion.

JM
a c 234 V Motherboard
a c 143 G Storage
June 27, 2011 11:09:47 PM

Yes... SATA II Vertex 2 in RAID0 will perform better on the SATA III contoller. Their speeds will be able to surpass the SATA II limits of 300 Mb/s and should perform closer to the 400 Mb/s range.
June 27, 2011 11:13:10 PM

But shouldn't two SATA 2 SSDs in RAID on a SATA 2 motherboard technically run at ~250mb/s + ~250mb/s since they each have their own sata connection? Would the SATA2 motherboard constrain the whole raid array to 3gb/s, or would they be able to theoretically run at 6 gb/s since they are two drives on separate 3gb/s connections?

I might be a little confusing, do you understand what I'm trying to get at?
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a c 234 V Motherboard
a c 143 G Storage
June 27, 2011 11:48:32 PM

You are right & wrong on both accounts in a way.

Yes... The Vertex 2 are SATA II drives but when they are in a RAID0, it allows them to perform above their SATA II limits on a SATA III controller. This is the benefit of a RAID0 setup but with the inherent added risk of potential data lose.

No... Two Vertex 2 in RAID0 doesn't equal SATA III drive. You gain a speed increase with the RAID setup but it doesn't make them SATA III. They are as good as one large SATA III device, like the Vertex 3 or Patriot Wildfire.

I hope this helps or have I just confussed you more :) 
June 27, 2011 11:58:00 PM

I see what you are saying. But what you are implying is that when I have 2 Sata 2 SSDs in RAID0 on a SATA2 motherboard the entire RAID array is limited to the 3gb/s, yet i was told it can achieve double that since each SSD is using a separate connector which each can go up to 3 gb/s.
a c 234 V Motherboard
a c 143 G Storage
June 28, 2011 12:07:13 AM

You are correct... Your RAID0 is limited by the SATA II controller. The drives act as one and will be limited by the max speed of the SATA II controller. When you plug it into SATA III controller, you RAID0 setup will be limited by the bandwidth of the SATA III controller even as a SATA II SSD.

As for the Double, this would be true for a mechanical drive to a point, as they don't come close to saturating the SATA II bandwidth. A SSD comes very close on it's own of reaching those limits without a RAID setup.
June 28, 2011 12:27:39 AM

Uh, SATA 2 transfer limit is 3 gb/sec, much faster than the capability of your SSD's. Nevertheless I have read that SSD's perform better on a SATA 3 connection. Two drives in RAID 0 should be about twice as fast for both reading and writing. Since each drive has it's own SATA connection I presume that your total speed limit will be double for the RAID 0 array. Look at some benchmark reviews.
June 28, 2011 12:47:40 AM

Well rocketman, I'm not sure what speeds you are basing your claim that 3 gb/s is faster than my SSDs on, because you are wrong. My ssds get rated at about 500 megs per seconds, which is faster than 3gb/s
June 28, 2011 1:17:14 AM

Yes, that is exactly what I am referring to. That is the whole point of this thread is discussing RAID 0 speeds on SATA2 vs SATA3. I was saying I get nearly 500 in the RAID 0 Array.

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a c 257 G Storage
June 28, 2011 6:34:32 AM
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Let's try this in plain English.

Using two SATA 3Gb/s ssd's in a Raid 0 array on a SATA 6Gb/s motherboard will result in some improvement in performance over a SATA 3Gb/s motherboard. The improved performance will not be equal to two SATA 6Gb/s ssd's in a Raid 0 array on a SATA 6Gb/s motherboard. The improvement is usually a small percentage. Individual performance results will vary.

I just checked several references. You would not notice the increase in performance. You would have to run benchmarks to see any difference.
June 28, 2011 3:09:00 PM

Best answer selected by jmills204.
June 28, 2011 3:10:23 PM

Alright, that is actually what I was originally predicting but I wasn't sure. I already have 2 SATA2 SSDs and am upgrading to a new chipset and processor for entirely different reasons, I was just curious about the disk performance.

thanks for clearing it up Johnny
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