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Re: Moving /tmp to tmpfs makes it useless

On 06/01/2012 06:50 PM, Goswin von Brederlow wrote:
> There is also no problem with having large files in tmpfs. Only
> requirement is that you make tmpfs large enough and add enough ram
> and/or swap to cope with it.

Well, there's the problem that it will take some memory at least. So
either your tmpfs is too small, either it eats all your RAM. None are
good options, unless you have a ridiculous huge amount of RAM available.
And that's why we shouldn't have it *by default* (that's the only thing
we are discussing here, not the fact that tmpfs is good or not, please
don't "hijack" the debate).

> All the complaints about /tmp as tmpfs come down to one simple issue:
> The size of the tmpfs isn't chosen well. It would be more constructive
> to find a better heuristic for the size there.

No. The complain is that it will never be big enough for some cases. If
you tell me that it should be twice as big as now, then I'll tell you:
what if we have to handle files twice as big as what you thought to
begin with? If you tell me 4 times, I'll tell you about files 4 times
bigger as well, and so on...

So it all goes down to a simple fact: in nearly all cases, we have a lot
more HDD space than we have RAM, which is why /tmp needs to be using the
HDD. There's never a case where tmpfs /tmp will be big enough to handle
all situations, while using HDD has a lot more chance to be able to cope
with it.

Anyway, if you're an expect, no problem, choose tmpfs if you want. But
don't force it to all users as a default which might break and that some
users wont understand. This is just too risky to have some users saying
"linux is crap, libreoffice can't open big PPT files, it gets horribly
slow, then crashes the whole system so much that I have to reboot".
Probably that's wrong, but it's still going to be the comments of our
users. Will you be watching debian-users@l.d.o and our forum, and
explain each of them? Will you take the time to explain this to my wife
and my mom (good luck...)?



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