[rescue] using big hard drives in Ultra 5/10's?

[jjhartley at att.net]

I've been using OpenBSD 3.7 on a Ultra 5 for several weeks now after I swapped out the original 9GB Seagate Medalist for a 160GB Seagate Barracuda.  Everything seemed fine until I ran disklabel and saw that a number of sectors at the end of the drive were unaddressable.  Okay, I'm running into the 128GB (ATA-6?) barrier & need to reset the disklabel such that it simply appears to be a 128GB drive.  I attempted to limit the number of total sectors to 268,435,456 (originally 312,581,808...) given:

128 GB * 2^30 bytes/GB
---------------------- = 268,435,456 sectors
512 bytes/sector

...through disklabel's editor, but the number of sectors reported for the entire drive (partition c) remained at the original value of 312,581,808.  I then attempted to change this manually and began creating individual partitions/mount points but I suddenly was no longer able to allocate more than ~15GB even after reboots.  Can anyone pass on the incantation needed to limit this drive down to something that the U5 IDE controller can handle?  Thanks.

Jim