How to Re org the SQL 2008 database to have equal size data files

Question

Hello everyone -
I have I/O issue with our production system (SAP ECC 6.0 on Windows 2008 and MSSQL 2008).
Following are my I/0 stats in DB02 (since DB Start)
ECPDATA1     E:     Data       25.779     28.053     4.689     1,056.68     36.297     23.326     2.515     45.301     14.43
ECPDATA2     E:     Data       23.143     24.979     4.68     593.297     17.971     12.448     1.238     47.663     14.518
ECPDATA3     G:     Data   9.17     9.807     3.477     1,018.69     36.144     21.938     2.457     46.434     14.712
ECPDATA4     F:     Data  10.985     11.788     2.69     148.512     4.777     3.248     0.314     45.722     15.201
ECPDATA5     F:     Data       14.746     16.164     2.676     162.39     6.693     3.679     0.432     44.139     15.491
ECPLOG1      D:     Log        5.337     27.081     4.916     26.962     26.264     0.037     1.919     726.928     13.688
ECPLOG2      F:     Log     0.755     17.582     0.487     35.472     35.161     0.042     2.637     845.998     13.334
The fourth column is ms/op which is very high and also asymmetrical for all the data files.
Also, The data files are not of equal size
ECPDATA1     106,173
ECPDATA2     59,588
ECPDATA3     105,036
ECPDATA4     14,992
ECPDATA5     16,491
ECPLOG1       1,025
ECPLOG2             3,199
So ECPdata1 and ECPdata3 are about 105 GB while #4 and #5 are 14 GB and 16 GB each. As per SQL best practices, all the Data files should be of equal size to get the best performance.
How do I make the data files with equal sizes ?
Your help is very much appreciated.
Thank you
-TSB

Answer 1

Hi dudes!
The key here is that you manually grow your datafiles before the autogrown mechanism comes to play; in fact, SAP recommends setting the autogrow just to avoid the hypothetical case that should never arrive in which the DB administrator forgot about the database size and it ran out of space.
Otherwise, if you properly monitor and manage your DB you should always grant that at least 30% (to say) of free space is allocated in your datafiles. If you do so, the SQL Server engine should do the rest, as it follows a proportional filling strategy as you can read in SAP note 1238993.
In case your database is not still proportional, my advise is that you just manually grow the datafiles so that all them are the same size, and so SQL Server will do the rest. If you however need to addresss that immediately, you will need to reorganize your database, which is not just more sensitive and complicate, but also which involves some I/O intensive operations (check SAP note 159316).
Cheers!!
--Jesú