[rrd-developers] bus error when disk is full, with mmap & sparse file

Tobias Oetiker tobi at oetiker.ch
Thu Feb 2 07:22:28 CET 2012

Hi Richard,

Yesterday Richard Laager wrote:

> I stumbled across this thread:
> http://permalink.gmane.org/gmane.comp.db.rrdtool.devel/4102
> I've attached a patch that uses fallocate(), which may address this
> issue. Also, it should be faster than filling the file with zeros from
> userspace and may also decrease file fragmentation. I've only lightly
> tested the patch.
> Sorry my reply isn't threaded properly. I couldn't find an mbox-format
> archive to use for replying.

thanks for your patch ... I am a bit torn here:

* with the patch, we get performance and a sort of thin provisioning (files
  with holes).

* without the patch rrdtool  lives up to the promise of never running out of diskspace ...
  (with the patch, rrdtool would not crash but it would still run out of

maybe this 'creating files with holes' should be an optional
feature, available if rrdtool is compiled with fallocate ?

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900

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