Tim Moore wrote:
> [EMAIL PROTECTED] wrote:
> > I have an IBM DTLA 307030 (ATA 100 / UDMA 5) on an 815e board (Asus CUSL2), which
>has a PIIX4 controller.
> > ...
> > My problem is that (according to hdparm -t), I never get a better transfer rate
>than approximately 15.8 Mb/sec. I achieve this when DMA is enabled, - without it I
>fall back to about 5 Mb /sec. No amount of fiddling with other hdparm settings makes
>any difference.
> > ...
>
> 15MB/s for hdparm is about right.
Yes, since hdparm -t measures *SUSTAINED* transfers... the actual "head rate" of data
reads from
disk surface. Only if you read *only* data that is alread in harddrive's cache will
you get a speed
close to the UDMA mode of the drive/controller. The cache is around 1Mbyte, so for a
split-second
re-read of some data....
>
>
> "...four IDE devices can be supported in Bus Master mode.
> PIIX4 contains support for "Ultra DMA/33" synchronous DMA
> compatible devices."
>
> http://developer.intel.com/design/intarch/techinfo/440BX/PIIX4_intro.htm
>
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