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Memory allocation for PDB's

Chev2 Member Posts: 9
edited May 5, 2014 10:03PM in Multitenant

I was looking at doing some testing and PDB's and condensing down a production environment and was trying to figure out how memory allocation gets distributed to the PDB's. For example, lets say we have three production systems within in one CDB and one has active sessions of 100, and the other has 500, and another has 1000. Lets also assume we are using AMM for these systems. How does the memory get allocated? Supposedly Oracle support states that each PDB is assigned resources based on active sessions, which is normal. I am not sure I feel comfortable with that answer based on my examples above.  Oracle really doesn't have any documentation on this.

  I was wondering if anyone has this in production and how its been working for them?



  • Aman....
    Aman.... Member Posts: 22,919 Gold Crown

    Any PDB is a database and if you are considering the option of converting existing non-cdb databases into a PDB and plugging them into a 12c CDB database, the memory allocation of the CDB containing them should have that much memory allocated . For example, if I would have 2 non-cdb's each running with 700MB of RAM, I shall start the CDB instance with about 2gb of RAM (1400 MB for two instances and 600 extra for the CDB itself) and then shall monitor what is the impact over the performance. Again, this is not I shall consider as a best practice. How much each PDB wpould eventually use, I guess it would be a matter of investigation based on the workload it is incurring. I don't think that it's documented but I shall wait for Rp and others to confirm (and correct) .



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