[rrd-users] I have been told the .RRD is like a circle.....

[John Giordano]

no beginning and no end.  within is contained the knowledge we seek.

what I am not sure on is what I have heard on how RRD "compresses" the data over time.  What does this mean?

I understand that the .RRD logs don't grow and this is one of the many things that are cool about RRD and the fact it only generates the graphs when need be.

My question is this: if I issue this command one day and then issue the *exact* same command 30 days later or 60 days later the info retrieved is not identical.

The command is run via a Perl script I cooked up and then the data is stuffed into a MySQL database for archiving, trending, etc.  (hopefully billing soon too)

-----------------

here's the whole enchilada:

./rrdtool graph /dev/null --start 12/1/2002 --end 1/1/2003 DEF:inoctets=IP.ADDR.OF.DEVICE_16.rrd:ds0:AVERAGE CDEF:in=inoctets,8,* PRINT:in:AVERAGE:"%lf"

./rrdtool graph /dev/null --start 12/1/2002 --end 1/1/2003 DEF:inoctets=IP.ADDR.OF.DEVICE_16.rrd:ds1:AVERAGE CDEF:in=inoctets,8,* PRINT:in:AVERAGE:"%lf"

I take both outputs, multiply by 86400 (seconds in a day) and then multiply by 30 (days in month) and add the two together.

Which comes out to:

The bandwidth pushed over 1_2003 was 147386765961.79 bits

Or in GigaBytes... 17.1580777924729

that was run a month or so ago.

-----------------

Now I run the *exact* same command today (2/10/03 PST):

./rrdtool graph /dev/null --start 12/1/2002 --end 1/1/2003 DEF:inoctets=IP.ADDR.OF.DEVICE_16.rrd:ds0:AVERAGE CDEF:in=inoctets,8,* PRINT:in:AVERAGE:"%lf"

./rrdtool graph /dev/null --start 12/1/2002 --end 1/1/2003 DEF:inoctets=IP.ADDR.OF.DEVICE_16.rrd:ds1:AVERAGE CDEF:in=inoctets,8,* PRINT:in:AVERAGE:"%lf"


and I get:

144185382070.472 bits or 16.7853876564736 GigaBytes.

Any insight would be greatly appreciated.  Also thanks to the guy who posted the 95th percentile script!

Here's the output of .rrdtool info on the .RRD:

well...it's a lot of stuff.  Lemme know if you guys would like to see it.

Thanks,

John

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