Re: IDE Disk speed enhancements

David Monro (davidm@cs.su.oz.au)
Thu, 25 Apr 1996 20:24:48 +1000 (EST)


[lots of stuff about overlapped transfers on different ide interfaces]

"Marty Leisner" <leisner@sdsp.mc.xerox.com> writes:
> So it would make sense to configure two disks as /dev/hda and
> /dev/hdc, instead of
> /dev/hda and /dev/hdb?

Absolutely! If you have two interfaces, use them - makes a big difference.
Really speeds up fsck ;-) Seriously, for ide interfaces you really only want
one device per interface if possible.

(Actually it has been possible to do this for a very long time - I used to
maintain a patch which was a merge of the atdisk2 dual interface code (Delman
Lee I think?) and the Mark Lord ide enhancements patch back a while - the last
version (which is still on tsx-11) is for 1.1.2[234]. After that Mark merged it
and it all ended up in the distribution kernel. The original atdisk2 patches
probably predate 1.0 - but I only had one drive back then).

>
> I've never seen this written anywhere...

Until recently, having a second interface was pretty rare - I only had one
because I got lucky with a card sold to me. Now that everybody has motherboards
with two interfaces on them, or at least a soundcard with an ide CDrom, we
should point this out somewhere. These days the kernel will handle at least 4
interfaces, so I guess they should be filled hda, hdc, hde, hdg, hdb, hdd, hdf,
hdh. Anybody with an old machine with a single interface but with an ide cdrom
as well should move that second drive over...

>
> --
> marty
> leisner@sdsp.mc.xerox.com
> Member of the League for Programming Freedom
>
>
>