Enabling DMA on SATA

[freakmn]

Is it posssible/necessary to enable DMA on SATA (Serial ATA) hard drives? I have 2 SATA hard drives, and they show up as SCSI drives (/dev/sda + /dev/sdb). hdparm says that DMA cannot be enabled for SCSI drives, and won't do it, but I thought I remembered reading somewhere that you could. Thanks.

[mdwatts]

See if this thread (http://justlinux.com/forum/showthread.php?s=&threadid=109407&highlight=dma+sata) helps that I found with a JL forum search for 'dma sata'.

It could be you need a newer version of hdparm that supports SATA drives though this is only a guess. Perhaps the main hdparm website will have something on SATA drives.

[hard candy]

SATA Specs (http://www.interfacebus.com/Design_Connector_Serial_ATA.html)
When using anything with a DMA above 33 make sure your motherboard (or IDE controller) supports that speed, that you have set it correctly/enabled it in the BIOS, and do use the correct 80 pin IDE cable or SATA cable, or your disk will default to a lower speed.
Some disheartening quotes:
"I don't believe SATA is that much if any improvement
over ATA/133. I've read Net reports to that affect. Some
Mandrake users have posted SATA hdparm -Tt numbers on various
groups an forums, an they're all less then the numbers my
ATA/133 puts out. Actually most of 'em were closer to what my
ATA/100 drive gets.
At the moment there is no real improvement over ATA drives
because the SATA drives are really just ATA drives wtih a SATA
interface tacked on when they start designing drives around the
SATA standard, things will pick up and we'll have game on"

Some more quotes:
"I'm using the Intel D845PEBT2 motherboard/ sil 3112A/ bios version 4.1.45 and from hdparm -t /dev/hdx i got only 1.7MB/sec"

"Well I have the RAPTOR 37 GB drive set up with the Silicon Images card sent with the drive on an ASUS P4PE using Redhat 9.0. The result is YUCK! hdparm -t yielded 1.63 MB per sec."

I think the newer kernels support SATA so it is dependent on the kernel version as to whether the DMA is supported for those drives.