Re: /tmp as tmpfs and consequence for imaging software
On Wed, Nov 16, 2011 at 11:56:40AM +0100, Goswin von Brederlow wrote:
> Roger Leigh <firstname.lastname@example.org> writes:
> > As touched on in the bug report, I think that being able to store
> > 1.2GiB on /tmp is an unrealistic expectation. To qualify, I mean
> > to expect that to work *by default*. If you want to store such
> > large amounts of data, you will need to configure your system to
> > handle that, either by:
> > - provisioning of more swap and raising of the TMP_SIZE limit.
> > - disabling RAMTMP and using a disc-backed filesystem (either the
> > rootfs or dedicated /tmp mount).
> > Again, as mentioned in the report, due to the wide variation in
> > disc partitioning, filesystem utilisation and RAM capacity between
> > systems, we don't currently make *any* guarantees regarding a
> > minimum amount of space available in /tmp, when using a disc-backed
> > /tmp. If the rootfs fills up, /tmp will cease to allow creation of
> > new files. When using tmpfs, we do at least make a minimum
> > guarantee of having a certain amount of storage available (which
> > might albeit be used by other users).
> Correct me if I'm wrong but doesn't having a real filesystem for /tmp in
> /etc/fstab prevent tmpfs from being mounted there?
Not currently. The logic is that a tmpfs is mounted on /tmp if
- RAMTMP=yes, or
- fstab contains an entry for a tmpfs on /tmp, or
- root is readonly
An fstab entry for a non-tmpfs on /tmp won't currently prevent
the tmpfs from being mounted (it will be hidden underneath). This
would require setting RAMTMP=no. We could certainly improve the
logic here to make this a bit more robust. This is only the case
where you have an fstab entry /and/ RAMTMP=yes, or you have two
/tmp entries in /etc/fstab (one tmpfs and one not), so is really
only misbehaving when misconfigured.
.''`. Roger Leigh
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