Some time ago I wrote a short blog about dependencies between the number of enabled CPUs and how many databases you could build. Today we got another error when we were trying to create a new database. Here is the screenshot of the error.
If you can’t read it on a small screen it says “Create Database operation failed due to an unknown error. Refer to work request ID 2580d3ff-064e-4e6f-ab06-1327fd02f40e when opening a Service Request at My Oracle Support.” and provide an error code which is “Error“
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 22.214.171.124 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.
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.
Some time ago after the last Oracle Open World Christine Kivi wrote a blog stating that this is not “your father’s Oracle” anymore . The rapid development and continuous improvements in Oracle cloud is one of the signs that Oracle is changing. The generation 2 Exadata cloud at customer (ExaCC) was released on that last OOW 19 and initially had some limitations in options and interface. Oracle team promised to fix the issues and provide new functionality, planning some major updates in the next calendar year (2020). And so far as I can see Oracle team is working delivering the promised. Here I will try to review some of the new features implemented for the last several months. This is going to be a relatively long post. You can go to the bottom, read the summary and read in details only about changes you are interested in.
We’ve already discussed how to migrate databases from a standalone 12.2 database to a pluggable database (PDB) in a 19c container in the Oracle cloud. But what if the target container database (CDB) is already part of a Data Guard configuration and has several PDB in it? I will try to go through the main steps on how to do that without breaking the replication.
I see more and more Oracle databases are moving to the public cloud or to a hybrid cloud solution. Depending on the platform, size and used options it could be a different path but the general approach boils down to three main options – Oracle RMAN backup and restore, Oracle Data Guard or Oracle Data Pump with or without transportable tablespaces. Here I want to share our approach for migration from 12.2 standalone database to 19c RAC container as PDB in the Oracle Cloud Infrastructure (OCI).
The Oracle Zero Downtime Migration (ZDM) tool has been created to help with Oracle databases migrations. It saves time and automates many tasks. The saved effort is getting bigger and accumulates on scale when you need to move multiple databases. Behind the scenes it uses the very well known Oracle Data Guard. As a result you have good solid technology on the basis but at the same time limited to what the DataGuard can do and what it cannot. All details and documentation are available here. The tool works fine when all prerequisites are met but when you hit an issue you need to dig in and troubleshoot. Here I will try to share some experience with the ZDM troubleshooting. Please note that the information in the blog is actual for the 19.2 version of ZDM and it is possible that the behaviour will be different in the future versions.
Let’s imagine a typical working day, and you are getting a request to add a new database to your Exadata Cloud at Customer (ExaCC). If you are not familiar with the product, you can read about it in detail here. In short, it is an Exadata machine with a cloud interface, something like Oracle Exadata Cloud Service, but with the hardware installed in your datacenter.