Using TMPFS for /tmp and /var/run?

[Gary Palmer]

On Sat, Mar 31, 2012 at 02:57:38AM +0200, deeptech71 at gmail.com wrote:
> C. P. Ghost wrote:
> >Not clearing /tmp on reboot has been
> >the norm for way too long and it is too late to change now.
> 
> We either evolve or be in a stalemate forever.
> 
> >It's not just POLA, it also involves deleting data of unaware
> >users, and that should be avoided.
> 
> Mounting on a directory (/tmp) does *not* clear that directory, so 
> automatic data loss will not occur.
> 
> 
> Adrian Chadd wrote:
> > One of those reasons people stick/stuck with BSD is that we don't go
> > and change this stuff so quickly.
> 
> Yes, it would be a total of ~20 years before we finally decided to switch 
> to using TMPFS for /tmp.
> 
> 
> 
> Changes that potentially break the POLA can be categorized; a change has a 
> combination of the following properties:
> (1) the change fixes a bug (ie., the change is about something that should 
> have been different in the first place, eg., the change fixes the 
> misspelling of a command name)
> (2) the change can be prepared for (ie., enough time is given for the user 
> base to slowly switch the new method of doing things)
> (3) the change is evolutional (ie., the change is based on a decision to 
> yield a net benefit (not necessarily a benefit in all cases))
> (4) the change has priorly been given room (ie., is expectable as defined 
> by standards and the documentation)
> 
> The TMPFS-for-/tmp change obviously falls into (4), and surely into (3). 
> With the support of UPDATING entries, release notifications, and perhaps 
> announcements, the change also falls into (2). Furthermore, using TMPFS for 
> /tmp is analogous to adding assert()s to code. Noone is really breaking the 
> POLA that much.
> The TMPFS-for-/var/run should not even bother anyone.


Other than catching software that mistakenly assumes /tmp and/or /var/run
is persistent, what are the CLEAR advantages for changing the default?

Has consideration been paid to low-memory systems?

I think this discussion is fast becoming a bikeshed and distracting people
from real work on improving FreeBSD.  Without clear advantages from a
switch to tmpfs(5) or md(4) non-persistent storage the default should
stay the same, especially on release branches.  If people want that
behaviour, the switches are already there and while I may have missed it,
I don't believe there hasn't yet been suitable justification for making the
change.

Gary