RMAN clone query

Question

Hello DBA's
I'm using an 9i Oracle Solaris box.
I have a task to clone a TEST enviornment into a existing TRAIN enviornment using RMAN.
I edited the TEST spfile and ran the RMAN duplicate commnad - 'duplicate target database to train;' without deleting the existing datafiles on TRAIN.
RMAN automatically refreshed the datafiles with TEST's datafiles.
My query is:
1) Is this acceptable and will i land into problems later on OR should i have dropped the TRAIN database completley before doing a new clone?
2) In 9i (Solaris) there is no easy way to drop the database, should i have done a shutdown and dropped the TRAIN's datafiles manually?
You adivce/suggestions would be much appreciated!

Answer 1

It is always better to remove the "TRAIN" database before cloning "TEST" over to "TRAIN".
Consider the scenario :
Day 1: "TEST" has 5 datafiles in /u01. /u01 has filesystem space of 10GB and the 5 datafiles take up 6GB
Day 2: "TEST" is cloned to "TRAIN" for the first time. "TRAIN" is on /u02, 10GB, 5 files taking 6GB
Day 6: "TRAIN" is very busily used with a lot more data inserted. The 5 files in /u02 grow to 9GB. You add a 6th datafile of 1GB in /u03
Day 12: Your traning is over and you need to clone "TEST" to "TRAIN" again for the next set of trainees
Day 13: "TEST" is cloned to "TRAIN".
As has been pointed out, the clone would actually overwrite files. However, you'll find 5 files of 9GB being replaced by 5 files of 6GB. And a 6th file of 1GB "hanging loose" not being owned by anybody.
Wouldn't that cause confusion on, say, Day 19 ?
Here's another scenario :
Day 1: "TEST" has 5 datafiles in /u01. /u01 has filesystem space of 10GB and the 5 datafiles take up 6GB
Day 2: "TEST" is cloned to "TRAIN" for the first time. "TRAIN" is on /u02, 10GB, 5 files taking 6GB
Day 6: "TRAIN" is used for DBA traning. The trainee DBAs "reorganise" the database, using export import, down to 4 datafiles and taking 4GB only (because data has been deleted)
Day 12 : training is over
Day 13 : "TEST" is cloned to "TRAIN"
What do you see happening now ?
Here's a third scenario :
What about DBAs renaming datafiles (not just locations, but file names) during Training ?
Here's a fourth scenario :
Between Day 2 and Day 13, the "TEST" server storage is expanded and /u01 is 20GB. Also, "TEST" grows to 16GB in size. But the "TRAIN" server's /u02 is still 10GB.
What happens when you re-clone on Day 13 ?
At each refresh clone, you must consider that
a. file numbers may have changed
b. file names may have changed
c. file sizes may have changed