4.9, 5.1 boot failure after install

[danl at solvnet.net]

Hello,

I had 4.9 release working and did a clean install of 5.1 release over 
the 4.9 and ended up with boot failure after install. Using allBSD 
partition and standard MBR I get a missing operating system error. If I 
use the FreeBSD boot I just get "default F1" and a beep. Now trying to 
install the 4.9 gives the same results.

I'm using a Mylex DAC960ptl (accelraid 250) with the primary disk 
setup as JBOD. I set the bootable disk as active but everytime I go 
back to config fdisk the flag is not set. 

I then upgraded and flashed the RAID card, reformatted the disks and 
tried a 4.9 install, again with the same results.

Is there an issue with the DAC card geometry or BIOS? Or a subtle 
quirk that isn't documented yet?

thanks,
Dan