Solved SATA Connectors and Controllers

[lehnerus2000]

My motherboard (ASUS M3A) has:

• 4 SATA connectors (arranged in 2 pairs).
• RAID support.

Am I correct in assuming that each connector has a separate controller (i.e. 4 controllers)?

Would my HDDs perform better, if I attached one to each pair of connections (ignoring RAID)?

 

[Brink]

Hello Lehnerus,

Looking at your motherboard's manual, it appears that all 4 of your SATA ports share the same southbridge. It's not going to affect the performance of the HDDs no matter which SATA connector you have the HDDs plugged into.

Hope this helps,
Shawn

 

[lehnerus2000]

Thanks Brink

Thanks Brink.
I thought that might be the case (because of the RAID support).

Is it the "default" that each connection has a separate controller (i.e. the SATA standard)?

BTW, which section contains the relevant statements which reveal the "truth"?
I have the book, but I didn't notice any reference to the controller vs connections.
A brief Internet search didn't enlighten me either.

 

[Brink]

Yeah, each SATA port is handled separately by the same southbridge chip/controller on your motherboard.

 

[lehnerus2000]

Thanks for those links Brink

Thanks once again Brink.
As we used to say, "you are a gentleman and a scholar."

Surely one chip handling all the SATA connectors must be a bottleneck.
If not, one could simply attach more connectors to the same circuit and gain extra benefits.
There must be a point where adding more drives to the same chip, reduces the performance.
I assume that server boards must have different chip sets, or multiple controllers.

I noticed that my HDDs only use about 20% of the theoretical bandwidth.
I get nowhere near 300MB/s out of my HDDs.
It's closer to 60 MB/s sustained, copying between SATA drives (with occasional bursts exceeding that).
Obviously there are mechanical limitations.

This leads to more questions:
Where does the SATA data clock rate come from?
Does the SATA controller have its own clock or is it based on the motherboard clock frequency?
Does reducing the motherboard clock frequency slow down SATA transfer speeds?
Where does RAID fit into this?

Do you (or anyone else) know of any good articles about these subjects?

 

[GeneO]

Thanks once again Brink.
As we used to say, "you are a gentleman and a scholar."

Surely one chip handling all the SATA connectors must be a bottleneck.
If not, one could simply attach more connectors to the same circuit and gain extra benefits.
There must be a point where adding more drives to the same chip, reduces the performance.
I assume that server boards must have different chip sets, or multiple controllers.

I noticed that my HDDs only use about 20% of the theoretical bandwidth.
I get nowhere near 300MB/s out of my HDDs.
It's closer to 60 MB/s sustained, copying between SATA drives (with occasional bursts exceeding that).
Obviously there are mechanical limitations.

This leads to more questions:
Where does the SATA data clock rate come from?
Does the SATA controller have its own clock or is it based on the motherboard clock frequency?
Does reducing the motherboard clock frequency slow down SATA transfer speeds?
Where does RAID fit into this?

Do you (or anyone else) know of any good articles about these subjects?

You are confusing the transfer speed of the SATA link with speed your hardrive is capable of. You would only be able to utilize 100% of that available 300MB/s SATA bandwidth if your hard drive were capable of it. Typical hard drives have a peak read transfer speed of 100-120 MB/S (that is on the outer part of the platters) and an average between 50-90 MB/s. The only kind of device that could use that 300 MB/s would be an SSD drive or a several hard disk drives striped in a RAID configuration.

60 MB/s for a disk to disk copy is pretty good and typical.

Changing the Motherboard clock frequency will not affect your transfer rates. It is controlled by a separate chip with its own clock.

http://en.wikipedia.org/wiki/Serial_ATA

http://en.wikipedia.org/wiki/RAID

http://en.wikipedia.org/wiki/Hard_disk_drive

http://en.wikipedia.org/wiki/Solid-state_drive

http://en.wikipedia.org/wiki/I/O_Controller_Hub

 

[lehnerus2000]

Thanks GeneO

Thanks for those links GeneO.
"You are a gentleman and a scholar", also.

You are confusing the transfer speed of the SATA link with speed your hardrive is capable of. You would only be able to utilize 100% of that available 300MB/s SATA bandwidth if your hard drive were capable of it. Typical hard drives have a peak read transfer speed of 100-120 MB/S (that is on the outer part of the platters) and an average between 50-90 MB/s. The only kind of device that could use that 300 MB/s would be an SSD drive or a several hard disk drives striped in a RAID configuration.

I guess I phrased my questions/statements badly.
I am aware of the fact that mechanical HDDs in PCs, can't transfer data at 3 Gb/s (although SSDs apparently can).

Thanks for that transfer speed info.
Is there a "rule of thumb" about number of HDDs vs speed for RAID 5 configurations?

I'm not sure if everyone has seen this YouTube video:
YouTube - Samsung SSD Awesomeness

These questions were provoked by one of my friends, who claimed that he had to buy a $4000 Sager laptop (with an SSD) to edit videos.
For that sort of money he could buy several desktop PCs (18 cores, 24 GB RAM and multiple TB of HDD storage) and link them together into a personal render farm.

He's not a professional video editor and he doesn't play games.
I think that he just wants to "one-up" his work mates.