FYI, NetBSD has just got support for the LSI SAS controllers, such as that found on the Sun X4200. My patch to fix this was committed last night. (The work was a side project funded by TELES AG.)
Of course we'd much rather everyone ran Solaris on these machines, but if you need NetBSD for some reason, it works now.
Pullups to NetBSD 3 and 3.1 should be forthcoming.