[olug] Argh!

[Brian Roberson]

one word...

ulimit




----- Original Message -----
From: "Sam Tetherow" <tetherow at nol.org>
To: <olug at olug.org>
Sent: Sunday, December 15, 2002 11:24 PM
Subject: Re: [olug] Argh!


> You would have to check the source code for mozilla or gtfp but I would
> bet what the author does is open the file for writing when they go to
> save which will cause the file to be wiped.
>
> As for full memory and swap, many things write to log files or syslog
> and most programmers do not take the time to handle this gracefully.
>  When say your /var partition fills up and syslog can no longer write to
> file the os will buffer the writes in memory in the vain hope that some
> disk space free up, when this doesn't occur, memory fills up, then swap
> space, once swap is full the writes start failing, as well as any new
> memory allocation.  Most programmers do not take the time to gracefully
> handle a failed alloc beyond printf(stderr, "cannot allocation
> memory\n"); exit;  But even those that do what is the proper behavior?
>  How will apache serve a file if it cannot allocate the memory to read
> the file?    How is mysql suppose to handle a request if it cannot
> malloc memory for the temporary buffers it needs to build the results set?
>
> Nick Walter wrote:
>
> >Opening a file read/write on a full partition and then writing to it will
> >not cause any particular problem, unless the application attempts to grow
> >the file by writing beyond the existing EOF.  The growing will fail, but
> >even then the existing contents of the file will be unharmed.  I'm
speaking
> >from experience as I once had to debug an application I'd written that
was
> >running into exactly this problem.  If requested, I can provide a test
> >scenario + source code to replicate this behavior.
> >
> >I'm also curious how having a full partition will impact memory/swap?  Is
> >this another case of badly behaved applications or some naughty behavior
of
> >the Linux kernel that I've never encountered?
> >
> >Nick Walter
> >
> >
> >----- Original Message -----
> >From: "Sam Tetherow" <tetherow at nol.org>
> >To: <olug at olug.org>
> >Sent: Sunday, December 15, 2002 4:30 PM
> >Subject: Re: [olug] Argh!
> >
> >
> >
> >
> >>Nick Walter wrote:
> >>
> >>
> >>
> >>>I've filled up partitions in my time, even filled up / on a couple of
> >>>occassions.  RH Linux always impressed me by not crashing or having
> >>>
> >>>
> >horrible
> >
> >
> >>>seizures when it happened.  I've seen other Unices do a lot lot worse
in
> >>>
> >>>
> >the
> >
> >
> >>>same situation.
> >>>
> >>>
> >>>
> >>Run it a little bit longer, horrible things will start to happen :).
> >> Once mem and swap are full there isn't much you can do.
> >>
> >>
> >>
> >>>The only thing I can think of is that Mozilla perhaps erases/re-writes
> >>>
> >>>
> >the
> >
> >
> >>>bookmarks when you edit them?  I'm 100% in agreement with Adam that
> >>>
> >>>
> >nothing
> >
> >
> >>>in Red Hat or Mandrake Linux will arbitrarily delete files just because
a
> >>>partition is full.  The only thing that should happen is some processes
> >>>dying or freezing because they can't complete I/O.
> >>>
> >>>
> >>>
> >>It is poorly written applications that cause this.  As the program
> >>exists it opens the file to rewrite the data, when the open command is
> >>given there is no error since you are not trying to write anything to
> >>disk.  In doing so you have now managed to set the file marker at byte
> >>zero in the file.  You now try to write but alas there is no room on the
> >>disk so you get an error and the program will exit meanwhile leaving the
> >>file marker at 0, effectively wiping the file.  The better way to do
> >>this is to create a second file, write out the new data and then rename
> >>the file with the old filename.
> >>
> >>
> >>
> >>>Nick Walter
> >>>
> >>>----- Original Message -----
> >>>From: "Adam Haeder" <adamh at omaha.org>
> >>>To: <olug at olug.org>
> >>>Sent: Saturday, December 14, 2002 8:30 PM
> >>>Subject: RE: [olug] Argh!
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>What do you mean wiped clean? Even if the partition fills up, there's
no
> >>>>process that says "better delete everything in Adam's home directory".
> >>>>
> >>>>
> >How
> >
> >
> >>>>did the data get deleted?
> >>>>
> >>>>-----Original Message-----
> >>>>From: Adam Lassek [mailto:hayai2 at cox.net]
> >>>>Sent: Saturday, December 14, 2002 9:22 PM
> >>>>To: olug at olug.org
> >>>>Subject: [olug] Argh!
> >>>>
> >>>>
> >>>>This is one thing about Linux that has always pissed me off. The
> >>>>partition my home directory was in filled up (not even sure how that
> >>>>happened yet) and so every bookmark I've ever saved in Mozilla, gftp
or
> >>>>whatever has been completely wiped clean. Why does that even happen?
> >>>>_______________________________________________
> >>>>OLUG mailing list
> >>>>OLUG at olug.org
> >>>>http://lists.olug.org/mailman/listinfo/olug
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>_______________________________________________
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> >>>
> >>>
> >>>
> >>>
> >>
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> >>
> >>
> >>
> >
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> >
>
>
>
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