> In any case, it looks like this is probably the problem.  The 
> "raidctl" man page (although I wouldn't have expected this) says:
> "Note as well that RAID 1 sets are currently limited to only 2 
> components.  At present, n-way mirroring is not possible."
>
> I'll try with RAID1 across only 2 disks (and maybe 2 spares?) in the 
> next couple days and report if this fixes the problem.

I updated my RAID setup and I can now boot a RAID1 array just fine when 
using only 2 disks (instead of 4).

Thanks again,
Mike