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Re: Predicting Growth.

From: Ben <balvey_at_comcast.net>
Date: 21 Sep 2006 05:37:32 -0700
Message-ID: <1158842252.568441.294070@d34g2000cwd.googlegroups.com>

Brian Peasland wrote:
> Ben wrote:
> > Ent Ed. 9.2.0.5, DMT's on AIX5L
> >
> > There isn't really an accurate way to estimate growth of a database, is
> > there? I have a history of six months of my data file sizes, but even
> > with that there are too many variables envolved to determine that my
> > database is going to continue to grow at a rate of 50 gig per year.
> >
> > Even if you assume a constant rate of growth, how would you base your
> > projection?
> >
> > For example, lets say my datafiles grew 25G over the last six months.
> > At the beginning of that six months my database was 100G that is 25%
> > growth over the past six months.
> > Now looking ahead for a year. My database is now 125G, 25% of that is
> > 31.25G. Then six months down the road the database will be 156.25G, 25%
> > of that is 39.06G, etc etc. But that original 25% figure was calculated
> > from the 100G incarnation of the database. So that won't work.
> > Do I then assume that my database will grow at a constant size instead
> > of %? So my 125G db will be 175G by this time next year. This seems
> > more accurate, but I still think there are just too many unknowns to
> > actually come to an accurate answer.
> >
>
> The more data points you have, the better to accurately predict your
> trend. I put such data points into Excel and create a chart. I then add
> a trendline to the chart to see where my growth is going to go. You
> might want to consider that.
>
> Also, I'm not sure I quite agree with your example above. You start with
> a 100GB database that grows 25% in 6 months, which gives us 125GB. Why
> do you then assume that that you will have 25% growth, compounded every
> 6 months? Maybe you have linear growth, which means in the next 6
> months, you will grow 25GB for a total of 150GB. By compounding the
> percentange of growth, you are assuming an exponential curve.
>
> That being said, you may have exponential growth...I don't know. It may
> be more linear. Or, it may be a more complicated mathematical function.
> The more data points you have, the easier it is to tell.
>
> HTH,
> Brian
>
>
>
> --
> ===================================================================
>
> Brian Peasland
> dba_at_nospam.peasland.net
> http://www.peasland.net
>
> Remove the "nospam." from the email address to email me.
>
>
> "I can give it to you cheap, quick, and good.
> Now pick two out of the three" - Unknown

Thanks for all the useful replies. I don't agree with the exponential growth example either, it's compounding the growth from the original percentage. After I made the post, I went back and plotted each previous month, to come up with a fairly static avgerage growth size per month. Then I went back to the first data amount and projected it forward using that avg and it came to within 1 gig of the true amount. Still not precise but close enough for what I want. Received on Thu Sep 21 2006 - 07:37:32 CDT

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