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> From: maney@... (Martin Maney)
> On Sat, Apr 24, 2004 at 10:12:56PM +0100, David Cannings wrote:
>> On Saturday 24 April 2004 22:00, Sebastian B?hm wrote:
>>> With every instance of uml I start the free discspace of the
>>> root-filesystem on the host becomes less, this continues during the
>>> runtime of the uml instances. If I stop all uml instances all this
>>> discspae gets freed.
>>> But I cannot find where this discscape is exacly eaten (which file).
>>> The problem is : i have very limited disc-space in the
>>> so I want to move it to another mounted partition.
>>> - So What exactly is it (cannot find something in the documentation)
>>> - How to move it to a different partition
>> Where exactly is your /tmp mounted? The output of `mount` and `df -h`
>> might help here.
> I would think that the clue that he's seeing space disappear in his
> root filesystem would be enough of a clue, no? Surely there is no
> separate /tmp, so the UMLs are opening their memory files on the root
> Sebastian, UML opens a temporary file to mmap the virtual machine's
> virtual RAM - that's where the space goes to. You can't see anythign
> because the file is created, opened, and then unlinked, which leaves it
> existing only inside the (guest) OS, which is a fairly common Unix
> trick to make sure that a temp file will vanish silently away when its
> creator terminates. There are a number of things you can do, but
> what's often suggested is to provide space on a tmpfs mount, then
> direct UML to use that by way of the TEMP environment variable (I think
> it checks TEMP - I can't readily find a reference to check). Or it
> might be easier just to mount another filesystem on /tmp, which may be
> a good idea anyway.
> It isn't that secrets are never needed in security.
> It's that they are never desirable. -- Whitfield Diffie
that's it !
Thank you very much !!.
(there should be a visible note about this somewhere, or at least the
error-message when the disc is full should be somewhat more
informative, just says "disc full" )
related Questions: (I am not familiar with mmap() nor with
- is there a way of finding these space-eating, invisible files with
standard tools ?
- does this mean, that exactly the same amount of memory which is used
inside uml is needed as discspace ? (also shared ,buffers and cache ? )
- does every (writing) memory operation result in disc writes ?
- doesn't this make some kind of suspend-to-disc quite easy (if all ram
is in a file, then it should be possible to just stop uml, and restart
it if the file still exists, that way one can reboot the host without
rebooting the uml(s) )?
- how many "real" memory (RAM) is used on the host when a uml cosumes
for example 50MB + 0M shared +20MB buffers + 20 MB cached ?