Linux Hugepages and AUTO_ONLY in Oracle 19c.

Most Oracle DBA are sufficiently educated about benefits using large memory pages for Oracle database SGA to reduce overhead and improve performance. If you want to read more about it you can start from that Oracle blog or read it from other multiple articles and blogs. Oracle is using parameter use_large_pages to direct behaviour of an Oracle instance during startup.

In the previous versions before 19c we had three possible values – “TRUE”, “FALSE and “ONLY”. Since Oracle 11.2.0.3 the “TRUE” meant that the instance will allocate as many hugepages as free available in the system and get the rest from the normal small pages. The “FALSE” would tell it to not use the hugepages at all and the “ONLY” would be able to start an instance only if sufficient number of free hugepages is available in the system to fit all SGA in it. The “TRUE” was default for all databases. 

In the 19c version we got one more value – “AUTO_ONLY” and now it is the default value for Exadata systems running Oracle Database 19c. The description in documentation is not totally clear and sounds very similar to the description of “ONLY” value. Here is an excerpt from the documentation:

“It specifies that, during startup, the instance will calculate and request the number of large pages it requires. If the operating system can fulfill this request, then the instance will start successfully. If the operating system cannot fulfill this request, then the instance will fail to start.”

Let me show you how it works. Here is my sandbox with a 19c database and no hugepages is configured on the box by default. 

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Google Bare Metal for Oracle.

Since the first days of working in the Google public cloud there have been debates about the possibility to move an Oracle workload to GCP. The major concerns were coming not from the technical challenges but rather from Oracle’s licensing policies and guidelines. In the famous Oracle’s document about licensing Oracle software in the public cloud it was stated – “This policy applies to cloud computing environments from the following vendors: Amazon Web Services – Amazon Elastic Compute Cloud (EC2), Amazon Relational Database Service (RDS) and Microsoft Azure Platform (collectively, the ‘Authorized Cloud Environments’)”. So the Google Cloud was not listed as an ‘Authorized Cloud Environment’ and it was unclear how to apply the Oracle licensing there. I believe it will be sorted in time but in the meanwhile as a solution Google presented a Bare Metal Service as the platform for Oracle workload.

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The new 21 is already here for Oracle Autonomous.

You’ve probably already seen in the news that the Oracle 21c is available and saw some tweets and blogs about the new release. But did you know that not only DBCS with “normal” cloud databases available but also the Autonomous version?

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Cucumbers, coffee and chocolate or how to create non-cdb on Exadata Cloud at Customer.

For those who are puzzled by the title here is a short explanation. I didn’t pay too much attention to what I had in my fridge and one day I found only a couple of cucumbers, chocolate and some coffee. That was not too bad but I couldn’t call it a proper nutrition diet. It was at the same time when I was exploring a possibility to have a non-cdb 12.1 Oracle database on an Exadata Cloud at Customer (ExaCC). One might think the blog is about comparing the unusual diet with the non-cdb deployment on a cloud environment telling that you should not really use non-cdb as you probably shouldn’t eat only cucumbers, chocolate and coffee. But it is not true, the blog is how to create such non-cdb on an ExaCC.

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Oracle multi-tenant: PDB scope parameters and where you can see them.

Working with Oracle multi-tenant architecture gives us some obvious benefits but also some challenges. What if we want to change a system parameter but only for a certain pluggable database (PDB) and keep it default for all others? Starting from 12.1 Oracle provides the ability to modify parameters on PDB level. If you look to a reference documentation for database parameters it states clearly whether it can be applied on CDB level or not. And with every new release we have more and more parameters which can be changed on PDB level. It has grown from 185 for 12.1.0.2 to 194 on 19.7.0.0.

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