Oracle has done a great job with the wait interface. It has given us the opportunity to profile the time spend in Oracle processes, by keeping track of CPU time and waits (which is time spend not running on CPU). With every new version Oracle has enhanced the wait interface, (more...)
Recently I am involved in a project which requires a lot of data to be extracted from Oracle. The size of the data was so huge that the filesystems filled up. Compressing the output (using tar j (bzip2) or z (gzip)) is an obvious solution, but this can only be (more...)
This is the fourth post on a serie of postings on how to get measurements out of the cell server, which is the storage layer of the Oracle Exadata database machine. Up until now, I have looked at the measurement of the kind of IOs Exadata receives, the latencies (more...)
Exadata is about doing IO. I think if there’s one thing people know about Exadata, that’s it. Exadata brings (part of the) processing potentially closer to the storage media, which will be rotating disks for most (Exadata) users, and optionally can be flash.
But with Exadata, you either do normal (more...)
When you are administering an Exadata or more Exadata’s, you probably have multiple databases running on different database or “computing” nodes. In order to understand what kind of IO you are doing, you can look inside the statistics of your database, and look in the data dictionary what that instance (more...)
Exadata gets its performance by letting the storage (the exadata storage server) participate in query processing, which means part of the processing is done as close as possible to where the data is stored. The participation of the storage server in query processing means that a storage grid can massively (more...)
The purpose of this post is to show what the wait event ‘cell smart table scan’ means, based on reproducible investigation methods.
First of all, if you see the ‘cell smart table scan’ event: congratulations! This means you are using your exadata how it’s intended to be used, which means (more...)
This post is about database writer (dbwr, mostly seen as dbw0 nowadays) IO.
The testenvironment in which I made the measurements in this post: Linux X64 OL6u3, Oracle 184.108.40.206 (no BP), Clusterware 220.127.116.11, ASM, all database files in ASM. The test environment is a (more...)
This post is about log writer (lgwr) IO.
It’s good to point out the environment on which I do my testing:
Linux X64 OL6u3, Oracle 18.104.22.168 (no BP), Clusterware 22.214.171.124, ASM, all database files in ASM.
In order to look at what the logwriter (more...)