Upgrade from 6.4 to 9.1?

[Fbsd8]

Dan Nelson wrote:
> In the last episode (Mar 16), Drew Tomlinson said:
>> I have an old system happily running 6.4 but am finding that it can no
>> longer download or build a ports index.  Thus I guess it's time to
>> upgrade.
>>
>> What "gotchas" do I need to look out for?  In the past my upgrades have
>> always been simply downloading new source, reviewing kernel config file,
>> and then rebuilding the system.  Any ports that didn't work after that I
>> would just rebuild as well.  However I've never waited this long to
>> upgrade.  Do I need to do anything different?
> 
> You won't be able to do a straight source build from 6.4 to 9.1; too many
> low-level changes like Makefile syntax and compiler options have changed. 
> If you are comfortable with temporarily disabling non-essential things that
> fail to build, it is definitely possible to do a long jump to 9.1, but it'd
> be safer to either hop from 6.4 -> (7-stable or 8-stable) -> 9 doing
> buildkernels and buildworlds, or just do a binary upgrade of kernel and base
> system to 9.1.
> 

The best approach is to backup your user data and do a fresh install 
from 9.1 cdrom. You will bypass a bunch of headaches which may in the 
end force you to do a fresh install anyway. And it will save you a lot 
of compile time. It's alway a good feeling to know you have a pristine 
system when you start having problems.