21 Oct
2004
21 Oct
'04
8:39 p.m.
On Thu, 21 Oct 2004 23:47:11 +0200, Robert Epprecht <epprecht(a)solnet.ch> wrote:
Mark Knecht <markknecht(a)gmail.com> writes:
No - it's done in hardware. If one drive REQUIRES that the cable run
at 33MHz, and the other drive can operate at 33/66100MHz, then the
controller sets the cable at 33MHz and leaves it there. The EIDE cable
cannot change frequency while operating.
I think the good news is that your equipment looks new enough that you
will likely not have this problem. It's more an issue when mixing new
and old hardware.
On Thu, 21 Oct 2004 19:43:16 +0100, anahata
<anahata(a)treewind.co.uk> wrote:
> On Thu, Oct 21, 2004 at 07:44:11PM +0200, David Baron wrote:
> > was told that the slower CD device will
slow down the HD.
> It used to be true. It was often
misrepresented as the CD slowing the HD
> down to its speed
No - this actually is true. An EIDE controller
that is compliant with
the ATAPI specs will recognie that one drive operates with the cable
going 100MHz, while the controller recognizes that the CDROM only
works when the cable goes 33MHz or 66MHz. since the two drives are on
the same cable the EIDE controller sets the cable speed at 33MHz and
therefore you get less throughput from the hard drive. I wasn't aware
until about 2 years ago that the controller had to do this. There are
some good white papers somewhere on the Seagate or Maxtors sites if I
remember correctly.
So you say, that it is the *controller* who does it?
It can not be influenced (set) by the kernel, by hdparm or something?
This sounds like it could be easy to figure it out with dmesg, hdparm
or something comparing results with and without connecting the optical
drive? What exactly should i look for?
Sure - run:
hdparm -tT /dev/hda
with and without the optial drive attached. (Optical should be /dev/hdb)
Do it again with the second drive using
hdparm -tT /dev/hdc
Robert