SATA, 3G Questions

[skankinred]

'm using a SATA3G DFI Mobo and have some questions about using SATA3G and I devices together.
If a SATAI HD is primary, and a SATA3G is secondary; will the SATA3G HD only run at SATAI speeds?
If a file transfer from SATA3Gs to SATAI drive is initiated, would the read from SATA3G only run at SATAI speeds?

I understand that I/O Performance not the same as the read/write performance of the drive. I'm talking about when you are running multiple drives. Say you are downloading using Bittorent on one HD(which uses a lot of activity), and copying a file from another SATA3G to another SATAI drive.
The advantage with the SATA3G is that the entire SATA controllers throughput is 3Gb/s.
I can see 3 HD's transfering information at the same time can easily overwhelm a SATAI controller; going over 150mbs.

The question is if there are SATAI devices in conjunction with SATA3 devices, would the controller throttle down to SATAI? Or would the SATAI interface on that drive simply limit it to the 150mbs and the total bandwith on the SATA controller(including all other HD's bandwith) still be 3Gbs?

 

[nobly]

I would say it depends on the SATA controller chip itself. I do not think it would throttle the entire controller down to SATA 1.

Also the port multiplier (if applicable - probably is) would be taken into account as well.

You should note that single HDD's on SATA 1 or SATA 2.0 would probably transfer at rates that are much lower than the spec calls for. HDD's typically max out at 60-80MB/s. SATA 1 is 150MB/s and SATA 2.0 is 300MB/s. So even if you read from a 2.0 drive to a 1 drive, your HDD's would be the bottleneck, not the interface.

As for the theory of it all, I'd say it would throttle down a controller port (and any other HDDs connected via a port multiplier) to SATA 1. But it would not throttle down other controller ports. Again, depends on the auto negotiation that the controller has. :?

 

[michaelahess]

That's a silly questions SATA is an entirely different interface type, IDE and SCSI share but SATA doesn't like wusy said.

I have to say though, if the sata1 and sata2 drive's are similar they will work at similar speeds when transfering between the two, no drive comes close to using the sata 2 data rates, or sata 1 for that matter, which is why they are great for large RAID arrays (single controller per drive)

 

[nobly]

Ok well first off, we gotta get some things straight. Just because you have 4 SATA ports on your motherboard does not mean you have 4 SATA channels.

More likely than not, you'll have 1 SATA channel that is going through a port multiplier to get you those 4 SATA ports. Which means the bandwidth on that channel is shared between those 4 SATA ports. This is why SATA II is here. At 300MB/s, 4 HDD's in RAID 0 can max out a SATA II channel.
At 150MB/s, 2-3 HDD's in RAID 0 can max out a SATA 1 channel.

It does seem like semantics, but its important to distinguish. The only real way to tell what your motherboard has is to find out what SATA controller chip it has then go look it up.

 

[michaelahess]

Point taken, though a lot of solutions have dual controllers so you have 2 hd's per controller, instead of 4, the key one in fact is nForce 4 (not sure of the lower end ones), check here:

http://www.nvidia.com/page/pg_20041015215635.html

Read the tech brief about 2 pages down.

The Via VT6421 is similar:

http://www.via.com.tw/en/products/peripherals/serial-ata_raid/vt6421/

And my raid controller, the Highpoint Rocket Raid 2320 has a full 8 channels for eight drives (as do most add-in RAID 5 or 6 controllers):

http://www.highpoint-tech.com/USA/rr2320.htm

I don't know about others and don't feel like looking right now but even two drives in a RAID 0 on 1 channel will be hard pressed to max that one controller out.

I imagine the low end SI or via chips may combine 4 into one but who knows. Would be nice if anyone knows and could post though....