12c to 19c upgrade

[satish]

Dear erman,

We are upgrading our ebs database from 12c to 19c

Creating CDB:

1) How much free space is required in tablespaces when we create container database?

2)Can we place the container datafiles in the same location as non container database.

Pls,we need your help.

Thanks,
Satish

[ErmanArslansOracleBlog]

1) Most user data resides in the PDBs. The root contains no user data or minimal user data. The disk storage space requirement for a CDB is the space required for the Oracle Database installation plus the sum of the space requirements for all PDBs that will be part of the CDB.
2) In general you should not. It is not a best practice. Risky In general you must not overwrite any of the datafiles residing there. At least they should not be in the same directory.

[satish]

Thanks for the update.

This is ebs database and we are upgrading from 12c to 19c.

Any recommended free space values for system,sysaux or any other tablespace before we create CDB.

Thank you

[ErmanArslansOracleBlog]

For CDB, these are not things that too much to worry about on day1.
When you create a CDB you will have sysaux,system,undo,users,temp. (for root) & sysaux,system,undo,users,temp(for pdbseed)
In 19C for instance; there are default sizes for these tablespaces.. For instance for CB root -> SYSTEM tbs size 880MB, SYSAUX tbs size 440MB
Just use DBCA to create the CDB and then monitor it.
It depends..
**For instance if you take lots of CDB level AWR snapshots, then your CDB SYSAUX should be a little larger.. (FacT:The CDB-level snapshot data is stored in the SYSAUX tablespace of a CDB root. The PDB-level snapshot data is stored in the SYSAUX tablespace of a PDB.)
You need to check Oracle database Administrator’s Guide -- Creating and configuring a CDB..
But again.. It depends.. Create a default one and monitor it.

Some other facts & recommendations:

There is a separate SYSAUX and SYSTEM tablespace for the CDB root and for each PDB.
A default temporary tablespace exists for every container in the CDB. Therefore, the CDB root and every PDB, application root, and application PDB has its own default temporary tablespace.
The size of the SYSAUX tablespace is determined by the size of the database components that occupy SYSAUX. You can view a list of these components by querying the V$SYSAUX_OCCUPANTS view. Based on the initial sizes of these components, the SYSAUX tablespace must be at least 400 MB at the time of database creation.

[ErmanArslansOracleBlog]

Note that, when you create CDB using DBCA on 19C, those tablespaces come as autoextend enabled...(I just checked it.. so you can check it as well)

[satish]

Helpful.Thanks for the information.Sire i will monitor.