elliott-brennan <[email protected]> writes:
> I got home (from a very good day) and found my machine with a message
> on the screen (in front of Thunderbird) saying that I had less that 4%
> of my /home space left and did I want to start Konqueror to resolve
> this.
>
> Of course, I said yes. Then the whole GUI froze and I ended up
> rebooting and logging-in in safe mode. On checking the disk space:
>
> df -h
>
> I found I had used 79% of my /home space (500G SATA drive with 412G on
> /home).
[...]
> Can someone please provide me a bit of an idea as to what this may
> have been about?
Well, I can't explain why you got the warning, or if it is a genuine
warning or a bug, but I can perhaps shed some light on a corner of Unix
that might explain things:
Under Unix, if a process opens a file, then deletes it, without closing
the file, it remains in existence until the process exits. It can, for
example, continue to write to the file.
One of the traditional ways to run out of space on a Unix machine, and
to confuse the heck out of a new sysadmin, is based on this:
You start a process that, for some reason, spews a huge amount of junk
out, such as bogus warnings or over-verbose logging, and send that to a
file.
Then, the new admin notices the huge file after a while and deletes it,
but the process doesn't close the file — it continues to write it in the
background.
Give it a little time and the admin starts to wonder why there is only a
few percent of disk space free, but nothing shows up using it with du(1)
and friends...
Worse, a reboot cures this — because as soon as the daemon stops running
the file system will free the file, returning the disk space to the free
pool...
Regards,
Daniel
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