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Re: how to increase space for tmpfs /tmp



On 28/03/12 18:32, Roger Leigh wrote:
On Tue, Mar 27, 2012 at 02:58:52PM +0000, Camaleón wrote:
On Tue, 27 Mar 2012 14:13:23 +0100, Roger Leigh wrote:
As the person who created these defaults, just a few points for everyone
in this thread to consider:

A common (and very persuasive) argument for not mounting a tmpfs on /tmp
and instead using the root filesystem is that by default we install with
a single large root filesystem, and /tmp gets to use all the free space
there.  This is certainly true, and is a major reason why we should
consider doing this.

I also share that feeling.

However, the following points also need to be considered:

- having /tmp on / means that / needs to be writable by default
- having "limitless" space on /tmp means it can be abused by
   both users and applications.  It can lead to breakage on systems with
   a limited /tmp if applications make the (incorrect) assumption that
   they can store whatever they like there.  It's more sensible to
   provide a minimum guarantee.
- /var/tmp exists, and should be used in many of the cases where
   /tmp is being filled.

It's hard to get a clear picture of what generally useful defaults
should be when you only get feedback from a handful of users.

IMO, the rule of thumb for applying a new default is asking ourselves if
the new default will cause any problem to the users. If yes, then don't
touch the old default and keep it the way it was. If we are not going to
get any improvement but just for the 10% of our user-base, then we are
failing the 90% of the rest.

I can understand that running out of space is annoying and
frustrating.  That's not the intent of the changes by any means.


Once I have internet at home and I can work on sysvinit again (I
just moved house and started a new job), I will certainly be looking
at this more closely.  Initially this will be looking at improving
the tmpfs defaults, but we can certainly look at not making it the
default.

Thank you for that. I do appreciate how much work goes into this sort of thing.

This change has caused me a number of (admittedly not too serious) problems. I don't run the latest hardware. I can't afford to. I chose Debian nearly 10 years ago because it was the only distro that I could find that I could get to install on what I had at the time.

Some of my PCs are very small and under-powered. I am somewhat proud of the fact that I manage to install and run Wheezy (cli only) on a PIMMX with 32MB of RAM and 2GB disk. I mostly use that machine as an ssh terminal to manage my other systems. Obviously 32MB of physical RAM is not enough to manage much in the way of tmpfs, unlike those of us who are able to run multiples of GB or RAM.

May I suggest that, if you're looking into the installer, that you consider setting a low memory limit on the use of tmpfs for /tmp. Something like: If system has < 256MB physical, set TMPFS=no ? This would need to apply to updates too.

I think the main issue I had was that /tmp was moved to ramfs without anycomment (that I can recall, I may be wrong) shown by apt-listchanges. I have been told that it was discussed in the developers list, but I'm not a Debian dev. I'm a user.

--
Dom


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