Hello:
On Fri, May 7, 2010 at 3:12 PM, straup <[email protected]> wrote:
> 2) There seems to be some hard limit on the number of RRAs I can define?
> Maybe?
>
> Here are the details:
>
> These are the RRAs I'm using, assuming that since the default (rrdtool)
> step for Ganglia is 15 (seconds) I should just be able to multiply
> everything by 4.
>
> It's not entirely clear to me whether I need to do the same for the
> rows. I don't think so but I am a bit dense that way, sometimes...
>
> "RRA:MIN:0.5:4:480" "RRA:MAX:0.5:4:480" "RRA:AVERAGE:0.5:4:480" \
> "RRA:MIN:0.5:20:2016" "RRA:MAX:0.5:20:2016" "RRA:AVERAGE:0.5:20:2016" \
> "RRA:MIN:0.5:240:720" "RRA:MAX:0.5:240:720" "RRA:AVERAGE:0.5:240:720" \
> "RRA:MIN:0.5:5760:365" "RRA:MAX:0.5:5760:1460" "RRA:AVERAGE:0.5:5760:365" \
> "RRA:AVERAGE:0.5:1:244" "RRA:AVERAGE:0.5:24:244" "RRA:AVERAGE:0.5:168:244"
>
> Then there's the second problem where, given the above I can never seem
> to get the last two default RRAs to load properly. Specifically:
>
> # "RRA:AVERAGE:0.5:672:244"
> # "RRA:AVERAGE:0.5:5760:374"
>
> They always fail with the following error:
>
> RRD_create: can't parse argument '"RRA:AVERAGE:0.5:672:244"
>
> ...Which seems to be triggered by the corresponding "else" block to this
> in rrd_create.c (~ ln. 166):
>
> if (strncmp(argv[i], "DS:", 3) == 0) {
>
> I'm not really a C programmer so at that point I decided I was about to
> fall in to a twisty maze of stuff I would gradually understand less and
> less.
>
> Any thoughts or (gentle :-) cluebats on all of this would be most welcome.
The limit is imposed by the number of arguments an option can have in
the configuration file (in this case gmetad.conf):
#define CFG_VALUES 16 /* max # of arguments an option takes */
from:
http://sourceforge.net/apps/trac/ganglia/browser/trunk/monitor-core/lib/dotconf.h
In reality, it seems that you can only have 15 arguments, as the last
one gets garbled, as indicated by the follow error message:
RRD_create: can't parse argument '"RRA:AVERAGE:0.5:5760:374"#012'
Why it's garbled -- I'm not sure yet.
Anyway, for you to get around this issue, you'll need to increase
CFG_VALUES to a larger number (perhaps 32) and re-compile Ganglia. I
don't see why we can't increase this in our code, but I'll let other
developers comment on that.
I've tested rrdtool creation with that number of RRAs (17) and it is supported.
Cheers,
Bernard
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