My hp xw6400 workstation (not on HCL) has said 631xESB/632xESB SATA controller. The BIOS has only options for IDE emulation or AHCI/RAID combined. When installing opensolaris 2008.05 in AHCI/RAID mode the machine goes into an endless reboot cycle. The solaris ahci driver may not attach to the controller, I don't know. Same problem with nevada. I then tried to install opensolaris in IDE emulation mode, the installation process went without any flaws. But the system is 4 times slower than linux for disk write performance (22 MB/sec vs 90 MB/sec), read is faster but still only half the throughput than with linux ext3 in ahci mode. Is there any chance to get ahci working on this box?

Opensolaris snv84 - snv94 seem to be working fine. However, write performance is horrible. 1mb - 2mb/sec tops. Already looking into a PCIe card solution to fix this.

So I ended up with an extra sas/sata controller (LSI3041E) in this xw6400 box. Disabling AHCI/RAID mode for the now unused sata ports via BIOS settings is enough to prevent the reboot cycle. snv101 is running fine now.