Casper H.S. Dik wrote:

>> IDE controllers are _not_ limited to any disk size, that's BS. This
>> is only a firmware issue...
>
> No it is not; supposedly, the IDE controllers in the U5/U10
> cannot do LBA mode and DMA at the same time *and* supposedly the
> SPARC drivers does not support addressing over 128GB either.

You obviously have no clue about what LBA and DMA is.

LBA ("Large Block Addressing" or "Lgical Block Addressing") is a adressing
is a addressing scheme to convert the Cylinders, heads and sectors a disk
uses for addressing into a number of available blocks, thus overcoming the
common limitations of a PC BIOS. This has _nothing_ to do with the
controller IC but is solely a firmware (BIOS) issue.

For a closer description of what LBA does have a look here:
<http://www.pcguide.com/ref/hdd/bios/modesLBA-c.html>

The problem with the U6/10 is that the OpenFirmware uses only a 28bit
addressing scheme which limits the addressable disk size to 128GB (or 137GB,
depending on how big a GB is).

DMA ("Direct Memory Access") simply means that the IDE controller can push
the data direct into the computers' memory instead of having to use the cpu
for that (Polling, used with the old PIO modes). This indeed is dependent
from the firmware _and_ from the controller but has absolutely _nothing_ to
do with the disk size. You can use 300GB disk in PIO mode if You want, it
will be slow like hell and cause a lot of CPU load but it will work fine.

>> If it really would be a firmware issue how comes that the 200GB disk
>> in my U10 works as a secondary drive with full capacity?
>
>
> That suprises me a lot because for the onboard controller, there are
> two reasons why it shouldn't work.

No, there aren't. As I said before the 128GB disk size limit is only a
OpenFirmware limitation (28Bit adressing scheme). As soon as the OS is
loaded a driver takes control over the IDE controller, and from this time
for a secondary drive You're limited only to the disk size addressable by
that driver. Sadly, the Solaris drivers take the disk size reports from OFw
when loeading, but long ago I somehwere found a description how to make the
driver requesting the disk size from the disk rather from OFw. I just
followed the description and it worked. The disk now contains two 80Gb /home
and /home2 directories and a 40GB ftp directory.

I can check if I still have the link.

Benjamin