OFA Doubts

[karthiarun]

Hi everyone...

I know that this is a silly question to ask. But could u explain the difference between the Oracle_home and Oracle_base. I have read in a document that Oracle_base is for OFA-Compliant databases. take the case of a sun E450 box and a D1000 which contains 12 drives which is mirrored. So we have six drives to play with.

What is the best way to install OFA-Compliant database and also i have read in a document that to keep Oracle_home as /u01/app/oracle/content/product/version. It also asks us to keep the Oracle_Base as /u01/app/oracle. So what is the point in keeping the Oracle_base and Oracle_home in the same disk. Is it a must to keep the Oracle_base in the same disk. This is a silly doubt but i am totally confused.

Thanks in Advance
Karthi

[Chintz]

Both ORACLE_BASE and ORACLE_HOME are parts of OFA complaince. ORACLE_BASE is the base directory for oracle thus it can be "/u01/app/oracle". ORACLE_HOME is the home directory for the oracle product. In plain english ORACLE_HOME resides on top of ORACLE_BASE, thus, ORAC LE_HOME will be "/u01/app/oracle/product/8.x.x".

I hope I was able to clear your doubt.

Chintz

[maachan]

Here's another way to look at it.
ORACLE_HOME is where Oracle is installed. If OFA compliant, it would be ORACLE_BASE/product/x.x.x
ORACLE_BASE is where database specific files should be stored. So there should be ORACLE_BASE/admin/sid_name for each database, sid_name being the instance name.

Example:
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=/u01/app/oracle/product/8.1.6
for instance 'PROD' you should have
/u01/app/oracle/admin/PROD/adhoc
/u01/app/oracle/admin/PROD/arch
/u01/app/oracle/admin/PROD/bdump
/u01/app/oracle/admin/PROD/cdump
/u01/app/oracle/admin/PROD/exp
/u01/app/oracle/admin/PROD/pfile
/u01/app/oracle/admin/PROD/udump

They can be on the same disk because no datafiles, controlfiles or redo logs should be stored in these directories, if you are OFA compliant.

[sambavan]

Let me also add a piece to the puzzle what would you do, if you want to host two different versions of oracle under the same user@host how would be your database configuration?

should it be

/usr/local/oracle/816 ---> ORACLE_BASE=/usr/local/oracle/816/app/oracle
and
/usr/local/oracle/817 ---> ORACLE_BASE=/usr/local/oracle/817/app/oracle


OR

you would include the new version installation under the same application


ORACLE_BASE=/usr/local/oracle/app/oracle816
ORACLE_BASE=/usr/local/oracle/app/oracle817

In this case wouldn't the oraInstall directory get confused? about the prior installation of old version?



Sam

[marist89]

Originally posted by sambavan
Let me also add a piece to the puzzle what would you do, if you want to host two different versions of oracle under the same user@host how would be your database configuration?

should it be

/usr/local/oracle/816 ---> ORACLE_BASE=/usr/local/oracle/816/app/oracle
and
/usr/local/oracle/817 ---> ORACLE_BASE=/usr/local/oracle/817/app/oracle


OR

you would include the new version installation under the same application


ORACLE_BASE=/usr/local/oracle/app/oracle816
ORACLE_BASE=/usr/local/oracle/app/oracle817

In this case wouldn't the oraInstall directory get confused? about the prior installation of old version?



Sam

Your ORACLE_BASE would stay the same; just the ORACLE_HOME would change. For example, if you had 816 and 817 installed, you would have:
ORACLE_BASE=/usr/local/oracle

and then the ORACLE_HOME for 8.1.6 would be:
ORACLE_HOME=$ORACLE_BASE/product/816

and the ORACLE_HOME for 8.1.7 would be:
ORACLE_HOME=$ORACLE_BASE/product/817

[sambavan]

Now comming to the point that if I want to create an instance with the same name wouldn't there be a name clash?

In truth there shouldn't be one? what if you want to do dome kind of upgrade by exporting and importing the 816 structure into 817 structure?

So would they both share the same $ORACLE_BASE/oradata, where I fear a clash could occour. Or at $ORACLE_BASE/admin
again a possible point for a clash. How do you deal with these?


Sam

[marist89]

Hmm, could you have an 817 instance named PROD and and 816 instance named PROD on the same box? As you point out, I wouldn't recommend it. Without looking, I would guess that it could be done.

If you have your environment variables all messed up and are pointing to a different home/SID/LD_LIBRARY_PATH than you should be, oracle won't let you start your database. I would guess oracle is going out and getting it's own shared memory based on certain environment variables.

[sambavan]

What if I get to seperate things in the base level, that way I would be having different basees as a result it would encompass the OFA structure in it. On this case since oradata, product, admin and etc starts from the $ORACLE_BASE, you could keep things different and functional. I'm planning to try this structure sometime this week and see how functional it is, in the mean time was curious to gather some opinions and suggestions to try out.


If I were to go with the above structure, I beleive that only point I would get stuck is the /var/opt/oracle/oratab, where I have to fiddle with things manually.

Any suggestions/opinions ??

Sam

[sambavan]

Does any one know form where and all, does oracle read the oratab file appart from the dbstart script.

It would be really great if I could split the oratab based on the version and then, I beleive that I would be able to rerun two parallel instance with the same name belonging to different versions.


Any way to twigue this issue???


Sam

[sreddy]

It also reads environment from oraenv(K-Shell) and coraenv(C-Shell) apart from dbastart scripts.

You have to customize environment scripts, but oracle doesn't recommend doing that.