I attempted to enabled the geom_mirror as detailed in the handbook. After rebooting I am receiving this error: Invalid memory access at &SRR0: 00000000.0743f4c &SRR1: 90000000.00003030 Same issue on the other identical system, the error is slightly different: Decrementer exception at &SRR0: 00000000.0743f4c &SRR1: 90000000.00003030 I can't boot either of them at this point, but they are not important. The two systems were built specifically for testing this. Screen shots of the error can be seen on the forum topic: http://forums.freebsd.org/showthread.php?t=33613