Hi All,

I hope someone can help me with this; I've bashed a good-sized dent
in my desktop and would like to stop before the desk breaks
altogether.

I have a spreadsheet that I track my server hard drive free space on.
It does some basic averaging on consumption and the like. What I
would really like to be able to do is forecast when I am going to run
out of space.

I know the basics of what I want to do and I am sure I have all of the
parts, I just don't know how to cobble them together in a cell and
have it spit out my answer.

Here is what I have:

- Column A = today's date
- Column B = free bytes on HD
- Column C = byte change from yesterday (Btoday-Byesterday)
- A standalone cell that averages Column C (average daily consumption)

So; it should be a relatively simple FORECAST or TREND to tell me that
in x-number of days, I will reach x-number of bytes available.

If some kind soul is willing to help me along on this path, the amount
of gratitude poured forth would be excessive.

Hi,
We have to assume the data is linear ( a plot of date vs free sapce gives a
straight line)
So y=mx +b (something about your words makes you sound British, if so read
y=mx +c) - the thing you learned in school. If you knew m and b then for to
compute an X-value for a specified Y-value you need X= (Y-B)/M

You can get M with SLOPE and B with INTERCEPT. so if you dates are in
A1:A100 ans space values in B1:B100 then with the required space value in F1
use
=(F1-INTERCEPT(B1:B100,A1:A100)/SLOPE(B1:B100,A1:A100)

If the data is non linear you will need to use LINEST (see
www.stfx.ca/people/bliengme/ExcelTips ). Alternatiively, make a chart, add a
trendline and use the exend feature of trendline to see where it get to the
specified x-value.
Best \wishes
Bernard



"Anonymous Coward" wrote in message
m...
Hi All,

I hope someone can help me with this; I've bashed a good-sized dent
in my desktop and would like to stop before the desk breaks
altogether.

I have a spreadsheet that I track my server hard drive free space on.
It does some basic averaging on consumption and the like. What I
would really like to be able to do is forecast when I am going to run
out of space.

I know the basics of what I want to do and I am sure I have all of the
parts, I just don't know how to cobble them together in a cell and
have it spit out my answer.

Here is what I have:

- Column A = today's date
- Column B = free bytes on HD
- Column C = byte change from yesterday (Btoday-Byesterday)
- A standalone cell that averages Column C (average daily consumption)

So; it should be a relatively simple FORECAST or TREND to tell me that
in x-number of days, I will reach x-number of bytes available.

If some kind soul is willing to help me along on this path, the amount
of gratitude poured forth would be excessive.

If you are assuming a linear progression, then

y = ax + b

use slope and intercept with your data to get a and b respectively.

set y equal to zero and solve for x


0 = ax + b
ax = -b
x = -b/a


Assume you have 200 gigabytes and the slope comes out to be -1.3 GB per day.
(a = -1.3GB)

b = 200 (for the date you installed the drive -

x = -200/-1.3 = 153.8 days

--
Regards,
Tom Ogilvy



"Anonymous Coward" wrote in message
m...
Hi All,

I hope someone can help me with this; I've bashed a good-sized dent
in my desktop and would like to stop before the desk breaks
altogether.

I have a spreadsheet that I track my server hard drive free space on.
It does some basic averaging on consumption and the like. What I
would really like to be able to do is forecast when I am going to run
out of space.

I know the basics of what I want to do and I am sure I have all of the
parts, I just don't know how to cobble them together in a cell and
have it spit out my answer.

Here is what I have:

- Column A = today's date
- Column B = free bytes on HD
- Column C = byte change from yesterday (Btoday-Byesterday)
- A standalone cell that averages Column C (average daily consumption)

So; it should be a relatively simple FORECAST or TREND to tell me that
in x-number of days, I will reach x-number of bytes available.

If some kind soul is willing to help me along on this path, the amount
of gratitude poured forth would be excessive.

Hi
I know how you feel - I've been there.
Sometimes we try to solve a simple thing with complicated
solutions. Dont look for FORECASTs or TRENDs. Give you an
example:
If you have 100 apples and you eat an average of 2 a day
then devide the available apples by the daily consumption
i.e. 100\2 = 50 days before you ran out apples!
In your case
Devide the free bytes on HD (Column B) by the result of
the standalone cell with the average daily consumption.
I would use the "\" instead of the "/" devider to get an
integer answer.

Good luck .

George



-----Original Message-----
Hi All,

I hope someone can help me with this; I've bashed a good-
sized dent
in my desktop and would like to stop before the desk
breaks
altogether.

I have a spreadsheet that I track my server hard drive
free space on.
It does some basic averaging on consumption and the
like. What I
would really like to be able to do is forecast when I am
going to run
out of space.

I know the basics of what I want to do and I am sure I
have all of the
parts, I just don't know how to cobble them together in a
cell and
have it spit out my answer.

Here is what I have:

- Column A = today's date
- Column B = free bytes on HD
- Column C = byte change from yesterday (Btoday-
Byesterday)
- A standalone cell that averages Column C (average daily
consumption)

So; it should be a relatively simple FORECAST or TREND to
tell me that
in x-number of days, I will reach x-number of bytes
available.

If some kind soul is willing to help me along on this
path, the amount
of gratitude poured forth would be excessive.
.

Thanks for the help with this! Once I get my data tweaked around a
little, it should fit the model quite nicely.

Have a safe and happy Christmas...



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