[mrtg] Re: rrd file size to store 5-min data for 1 yr

[Simon ter Veen]

maybe I am missing something but when a 5-min data log for oe year
approximately takes up 31MB this is IMHO a mayor disadvantage....with
MRTG our 1 yr old log files are at 80KB

or am I missing some huge advantage of rrdtool over mrtg besides rrdtool
lesser utilization of cpu and hdd while graphing.......

don't get me wrong, I just wanna graph some switch utilization
statistics with it(until now)

-----Original Message-----
From: Alex van den Bogaerdt [mailto:alex at ergens.op.het.net] 
Sent: Friday, May 09, 2003 1:10 PM
To: mrtg at list.ee.ethz.ch
Subject: [mrtg] Re: rrd file size to store 5-min data for 1 yr


On Fri, May 09, 2003 at 06:54:42PM +0800, Francis Borman wrote:

> I knwo that we can tune up the RRD, so that we can store as much data
as we
> like. However, the rrd size for just storing 5-min data for two days
is
> about 170kb!!! It seems that to store 1 yr 5-min data, the file size
must be
> 31 MB!!

Sounds right; multiply 170kb by (365/2) for approximate values.

> Let say, if I have one rrd per router interface, and if I got 1000
> interfaces to monitor, I must prepare 31GB for just data storage?!!!!!

Now you know why data consolidation is taking place...

Do you want to keep the data or not?

> It seems a huge capacity for a PC/Server!!!! It also takes a very long
time
> to retrieve data for one particular date!!!!! (That's why we need to
store
> 5-min data for a yr)

No, it doesn't take a long time (or at least it shouldn't).  The offset
in the file is calculated (very fast) and the data necessary to RRDtool
is fetched from it (also reasonably fast).

*If* you are going to display the 5-minute averages, no consolidation is
necessary so everything should be fast.

> We are now doing sth that archive all rrd every midnite and write a
script
> for data retrieval. When we comes up a situation that need to
reference the
> past data, we use that script to retrieve the archived rrd of that
date. It
> seems to work for somehow, but what if I need to retrieved data for a
> particular week??? It seems that we need another way to handle
it......

If you almost never need to use the historic data, just process the
request
by hand.  Don't automate.  Work from backed up data.

If you *do* need the data on a frequent basis you know it and you can
prepare
a suitable RRA in your RRD that has just the right resolution (for the
image)
and enough rows of data (again for the image).

I don't see the problem here, except maybe that you didn't define to
yourself
what your needs are.

HTH
Alex
-- 
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give
offence. Rather, it's the product of the direct,
cut-through-the-bullshit
communications style that is natural to people who are more concerned
about
solving problems than making others feel warm and fuzzy.

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