Hi,
at the moment it works on a ca. 12Gb primary partition in a 300Gb Disk (I'm sorry, I said 320 Gb in older mail). I should get a 20Gb hd in the next time and I'd like to make some essays with partitions size and type. But yet I don't know if this make sense; if you say that the problem could be for disks >128Gb, could I say that until 128 Gb on every disk you can install the Hurd on every partition? I tried a lot of possibility with partitions on my disk (300 Gb), but always at the end of the disk. Maybe the Hurd can't read datas only starting from a certain value, because after changing the partition table (the actuallay partition table is a primary ca. starting from 15 Gb after begin of the disk) I had no problem to install debian GNU/Hurd.Most likely it doesn't like large disks (probably >128 GiB)
Bruno