Before you build the cubes if you want to estimate what will be the size of the cube, then you you can use the formula.
Formula is:
IC = F x ((ND x 0.30)+2)
x NR x NP
where
F = ((ND+3) x 4bytes) + (22
bytes x NK)
= required disk space in
bytes
add
30% per dimension in the
fact table
100% for aggregates
100% for indexes
F = fact table size in bytes
ND = no. of dimension
NK = no. of key figures
NR = no. of records
NP = no. of periods
But as in your case you already have a cube and ODS that is ready so use the following calculatioins (This is for the cube)
Data on the BW side is in terms of "number of records" not TB or GB. The size, if required has to be calculated only. You have to either use the formulae as given at above, to translate the number of records into TB or GB or the easy way, if you want to do it for yourself, is to estimate from the data growth and put an intellegent guess on it. Depends how accurate you would want to be.
The exact method, however, still remains as under:
Go through SE16. For example if the cube is ZTEST, then look at either E table or F table by typing in /BIC/EZTEST or /BIC/FZTEST and clicking on "number of records", just the way we do for other tables.
If the cube has never been compressed (a rare case if you are working on a reasonable project), then you need to bother only on the F Fact table as all the data is in F Fact table only.
You can get the table width by going to SE11, type in the table name, go to "extras" and "table width". Also you can get the size of each record in the fact table in bytes. Next, you can find out the size of all dimension tables by doing this. The complete picture of extended star schema should be clear in your mind to arrive at the correct figure.
Add all these sizes ( fact table width + all dimension tables widths) and multply it by number of records in the fact table. this gives you total size of the cube.
If the cube is compressed, (as may be the case??) then you will need to add records in E table also becasue after compression, data moves from F Fact table to E Fact table, hence you need to look into the E Fact table also.. Hope this helps
This is all done for the Cube. For the ODS you can get direct info from DB02
