[installworld] Do We need /usr/obj

[Warren Block]

On Tue, 26 Jan 2016, Brandon J. Wandersee wrote:

>
> Warren Block writes:
>
>> On Sun, 24 Jan 2016, Brandon J. Wandersee wrote:
>>>
>>> Second: placing NO_CLEAN="YES" in /etc/make.conf will greatly reduce
>>> build time, though using it on anything but -RELEASE would probably be a
>>> bad idea.
>>
>> Why?  I use NO_CLEAN routinely to update between versions of 10-stable.
>> If there is ever a problem, it's easy enough to delete /usr/obj (faster
>> than 'make clean') and try again.
>>
>> Actually, this is part of a fairly involved build script that automates
>> the normal process.
>
> Well, my reasoning was that changes between builds of the releng/*
> branches are fewer, farther between, and usually trivial (from a code
> management perspective), while changes between builds on development
> branches might involve more drastic fundamental changes, moreso the
> longer one goes without building. Since the OP wants to always minimize
> build time (and prefers unattended builds), the increased risk of a
> failed build probably wouldn't be worth it. If a build fails one can
> always just demolish what's already been built and start over, sure, but
> that's not really a favorable argument if always minimizing build time
> is the ultimate goal.
>
> But I have to admit I've never tried it, and if it works, then I stand
> corrected.

It rarely has a problem for me, and typically takes only a third or a 
fourth of the time of a clean build.  That comes at the cost of having 
about 5G of disk space permanently tied up in /usr/obj.

An unattended build should be fine, nothing harmed if it fails.  I would 
resist doing an unattended install.