SATA, a lesson learned... (1 Viewer)

[pbb]

I always thought that one of the positive things of SATA was, that it did not have the Master/Slave thingy that old-fashioned ATA has. Boy, was I wrong...

I've build an HTPC case with a SATA harddisk (Samsung SP2504C) and SATA DVD drive (LG GSA-H62N). My motherboard (Gigabyte GA-MA69GM-S2H) has a cluster of 4 SATA ports on the edge (quite difficult to reach). I didn't see any important differences in the 4 ports, so I just plugged my HDD and DVD in the ones that were easiest to reach.

Over the last months I have started to use my HTPC more and more, and started getting bothered by it's slowness in some things. I couldn't even play an MP3 without stuttering if I was also copying some files over the network at the same time. And a complete reboot (which I hardly ever did, I just put the machine in standby) took 5 minutes!

I thought this was probably because of some different software and drivers I had been trying out over time, or maybe it had to do with the onboard network card (which uses CPU power), or maybe the new SQL-Server based TV-Engine. So I just thought I would do a clean reinstall, and see if there is a clear point where the slowness starts.

But before I started I did a reboot, and saw in the BIOS screen flashing by, that my DVD was reported as being a Master with my HDD as a Slave. "Huh, with SATA?" was my first reaction. Maybe it's just a "compatibility mapping" to support older software that doesn't know about SATA? Anyway, I decided to do a test, unscrewed the case, removed several components to get to the SATA slots, and just put one of the connectors in another slot. And yes, now the devices were both reported as being Slave, but on different channels. Okay, so are the other two ports then Master ports? I plugged them in there, and yes, both were now Masters on channels 2 and 3. (Still unclear why channel 0 was unused, and why there is no channel 1, but I guess I shouldn't ask too many questions.)

So I decided to see if this would make any difference. Well, I was thrown back into my seat! Where a bootup from power-off before took over 3 minutes, it now only took 45 seconds...

So kids, learn this lesson with me, and play around a bit with your SATA connections before closing the case!

The weirdest thing is still that I never saw any reports on this difference, my motherboard guide didn't mention anything about it either...

 

[gxtracker]

Thats weird. Your motherboard manual should have mentioned something about priority SATA ports on your motherboard, or at least numbered the ports so that you could make an educated guess as to what ports to use first.

While SATA doesnt have a master/slave configuration, many mobo manufacturers implement different chipsets for different SATA ports (for example; 2 ports are run from the southbridge, and the other 2 are from from an additional chipset. My old A7N8X deluxe board was like that), or build right into the SATA BIOS a form of legacy controls that display your SATA drives as PATA drives to the OS, so no additional drives are needed when installing the OS for the first time.

What kind of motherboard are you using so I can make a mental note to stay away from it?

 

[pbb]

The ports are numbered SATAII0 through SATAII3, but I wouldn't know what the difference between 0 and 3 is. I am now using 0 and 2, which apparently are both Masters. The booklet mentions nothing about priority channels, and according to the diagram all four are connected to the southbridge. As I mentioned, it's a Gigabyte GA-MA69GM-S2H. I am quite happy with it for the rest. (Apart from that the X1250 integrated graphics doesn't seem to be too well supported on Windows XP.)

Do you think I have triggered some sort of compatibility mode without knowing it?

 

[deebo]

ahci is the road to victory

 

[and-81]

ahci is the road to victory

Advanced Host Controller Interface - Wikipedia, the free encyclopedia