[rrd-users] Re: Memory usage on large RRAs

Fabien Wernli wernli at in2p3.fr
Sun Dec 4 23:31:07 MET 2005


On Sun, Dec 04, 2005 at 11:16:11PM +0100, Alex van den Bogaerdt wrote:
> Each DEF and CDEF will consume memory.  You can start by getting rid of
> as much CDEFs as you can.  Simple example:

I am doing something like that indeed.
I will drop some intermediate steps to see if it helps.

> Do you save lots of correlated stuff in the database?  If you are only
> using two out of ten DSes, RRDtool still fetches all ten DSes.  It may
> make sense to, for instance, keep ethernet errors in a different file.

For the graph I was just trying to make, I monitor:

For each node/rrd:
	for each CPU: user, nice, sys, irq, sirq, io and idle

Then I do a CDEF to sum up all CPUs
     Then a CDEF to sum up all nodes

I just tried to sum up only one CPU per node. I can do a few more nodes, but it seems
difficult to graph more than 100 cpus on a 2G RAM machine without getting
the annoying "ERROR while updating mydemo.rrd: malloc fetch data area"

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