The good news is that there *are* workarounds, like the dmraid module, which can be found here:
But for the Z11 sony-vaio-z-series case, it's been reported that what *does* work is to follow the instructions in this youtube video:
This will set up an Ubuntu Karmic with a soft RAID 0, with the Fake RAID disabled by the BIOS.
Other users have commented that disabling the onboard RAID is probably the best solution, even once Linux dmraid supports the chipset. The argument is that Linux software will often give at least as good performance as most onboard 'RAID controllers'.
There is a caveat to the RAID0 configuration: losing any drive can potentially destroy all your data. So another suggestion is to use
RAID10 (or RAID5) for speed/redundancy, or alternatively, to add all the drives to a linear LVM volume, giving you access to all the
space. This means you only lose what's on a single drive if it dies.