WD Raptor RAID 0 on SATA II vs SATA III

[brianstephens]

So here is my problem. I have an older motherboard with a Intel core i7 860. The computer has only two SATA III ports. I currently have an Intel 180gb SSD on one of the two SATA III ports. I can move the SSD to one of the SATA II ports, (with a loss of about 15% speed) and put the raptors on the SATA III, or I can keep the SSD on the SATA III, ant put the Raptors on the SATA II connectors.

I have looked for some benchmarks for the Raptors (300gb SATA III version) on both SATA II vs SATA III and I can't find anything.

Anyone have an idea on what the speeds are on SATA II vs SATA III on this drive ( http://www.newegg.com/Product/Produc...82E16822136929 )??

What would I loose with Raid 0 from SATA III to SATA II??

 

[ShintaiDK]

Just use the SATA2 for the raptors. It doesnt make any sense to put them on SATA6.

 

[tracerbullet]

Agreed, as fast as the Raptors are the SATA II won't hold them back at all, it handles data faster than the drives can put out. I don't think anything other than a new SSD would outrun SATA II.

 

[BFG10K]

Those Raptors are the second generation 300GB versions (WD3000HLHX), so they’re faster than the first version. SATA2 tops out at around 250-280 MB/sec, so a pair of them might exceed SATA2’s bandwidth:

With that said, in this case I think each drive would get ~280 MB/sec for itself, and they couldn’t exceed this individually. So you should be okay.

 

[brianstephens]

Thanks for the info. I thought that that would be the best way to do it.

Question, on Raid 0....

Lets say that each raptor could hit 150, combined that is 300, if sata II can only get 250-280, would I be limited? Or would each drive get the full 150 each (because they are each on their own channel) reaching the full potential of 300?

Brian

 

[BFG10K]

Question, on Raid 0....

Lets say that each raptor could hit 150, combined that is 300, if sata II can only get 250-280, would I be limited? Or would each drive get the full 150 each (because they are each on their own channel) reaching the full potential of 300?

SATA is point-to-point so it doesn't share bandwidth amongst other controllers and drives.

So I'm pretty sure each Raptor will get ~280MB/sec to itself, and neither drive can come close to saturating that on its own.

 

[groberts101]

you won't even come close to saturating each channel with those drives.

The sata chips MAX available throughput would be the deciding factor and it'll take many drives to do it on any sata3 chip made today. Both Intel and AMD can top more than 1Gb/s when combining SSD's in raids.. so it's moot with those much slower drives anyways.

 

[brianstephens]

Thanks everyone for your answers.

 

[murphyc]

Well it's not just about bandwidth. If the drive supports SATA Rev 3.x there are a number of other features the drive may support as well that you only get if it's on a SATA Rev 3.x controller. Maybe the most relevant is NCQ Streaming. To know if it matters, you have to test them both with your workload and see which better meets your requirements.

 

[MrX8503]

The drives get their own channel. Just like how you can hit almost 1GB/s with SSD Raid 0.

Edit: just saw someone posted this.

 

[groberts101]

Well it's not just about bandwidth. If the drive supports SATA Rev 3.x there are a number of other features the drive may support as well that you only get if it's on a SATA Rev 3.x controller. Maybe the most relevant is NCQ Streaming. To know if it matters, you have to test them both with your workload and see which better meets your requirements.

Kinda seems irrelevant for the OP's intended purpose of storage and likely mostly sequential transfers.

Maybe if the HDD raid was intended for a boot volume.. or database with tons of randomly accessed small files. Even then though.. from what I've seen so far the gains would be too small to worry about robbing the 6G ports and hindering the SSD's max available throughput.

Of course.. the point could be made that there will be no other volume available on the system which can make full use of the SSD's 6G speed anyways. 2 Raptors surely won't exceed the SSD's 3G ports speed. Well.. burst speeds will.. but they go away pretty quick once the cache is quickly expended with larger files.