[rrd-users] Increase RRA Size

[Bigras, Guy]

Wow. Thanks everyone for the fast replies.

Unfortunately "they" want to keep or see graphs for each "fake" consolidation (ie:daily, weekly, etc...).  My 1st attempt was one RRA with no consolation (steps=1) and a years worth of rows.  However Cacti would only create or show one graph.  One RRA = One Graph and as I said "they" wanted to see various graphs ... sigh.  Therefore if I want to add another graph with a 5/10 year span I'd have to create another RRA.  Is it possible ?

thanks again guys for your time.

Guy


-----Original Message-----
From: rrd-users-bounces+gbigras=telesat.com at lists.oetiker.ch [mailto:rrd-users-bounces+gbigras=telesat.com at lists.oetiker.ch] On Behalf Of Alex van den Bogaerdt
Sent: Friday, May 07, 2010 2:28 AM
To: rrd-users at lists.oetiker.ch
Subject: Re: [rrd-users] Increase RRA Size


----- Original Message -----
From: "Bigras, Guy" <gbigras at telesat.com>
To: <rrd-users at lists.oetiker.ch>
Sent: Thursday, May 06, 2010 11:08 PM
Subject: [rrd-users] Increase RRA Size


> Hi there,
>
> I'd like to add a new RRA to the RRD file.  Can't figure out how to do
> it.

and you don't need to.

> Here's some background information:
>
> I'm using Cacti 0.8.7e with rrdtool verion 1.3.8-1.
>
> I've setup my RRDs to use four custom RRAs instead of the default
> ones.
> The major difference is that there is no data point averaging being done.

If you think that you store data with no alteration whatsoever, be careful.
Only in very specific circumstances this will be true. You really need to
study normalization and consolidation. See further on.

> Here is my RRA setup (5 minute polling interval):

[partially cut away]
> RRA1: Daily> Consolidation: average> steps: 1
> RRA2: Weekly> Consolidation: average> steps: 1
> RRA3: Monthly> Consolidation: average> steps: 1
> RRA4: Yearly> Consolidation: average> steps: 1
> rows: 109440
> Timespan: 31536000

All your RRAs have consolidation function average and steps==1. That's
useless. RRAs 1,2 and 3 just contain parts of what RRA 4 contains.

> The reason there is no averaging is because the powers from above do
> not
> want to loose any data point.  They want to be able to zoom into any
> "peak" on the graph and be able to look at the real data as opposed to an
> average.

That explains why you would have one large RRA with steps==1 step. But it
doesn't explain why you have the other 3 setup as you have. Study the
tutorials, visit my site http://www.vandenbogaerdt.nl/rrdtool/


> However now they want to be able to keep more than a year's worth.
> Hard
> drive space is not an issue so I've opted for a ten year RRA.  I just
> don't know how to modify an existing RRD file to incorporate these
> changes.  I've tried some scripts to export data and import back but it
> doesn't seem to work.

10 years = 7*365 days + 3*366 days (leap years) * 288 rows = 1052064 rows.

Increase the size of RRA 4. That RRA contains the largest amount of
information. Any rows you add do not magically contain information you
didn't have before, but as soon as they are there, you can start building
history.

You already have 109440 so grow the RRA by 942624 rows.  And don't forget
that a new RRD is built, you need to check that RRA (to see if it really is
what you want) and then copy it over the old one.  And don't forget to
backup the previous one first.

You can keep the other RRAs (useless, but not in your way) or you can setup
the RRD in a different way. Explaining how would be a bit too much right
now. You could also consider to hire someone to help you, tutor you, or
both.

Regards,
Alex

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