One of the perks of teaching classes is that I get to research questions asked. In the last Exadata Administration Class I taught someone asked: can you have your disk groups in Exadata on normal redundancy yet have certain databases use high redundancy? This would be a good interview question …
The answer is yes, which I remembered from researching material on the 11g RAC book but I wanted to prove that it is the (more...)
I have been teaching the Enkitec Exadata Administration Class this week and made an interesting observation I thought was worth sharing with regards to IO Resource Management on Exadata.
I have created a Database Resource Manager (DBRM) Plan that specifically puts a resource consumer group to a disadvantage. Actually, quite severely so but the following shouldn’t be a realistic example in the first place: I wanted to prove a point. Hang-on I hear you say: you (more...)
I didn’t intend to write another blog post yesterday evening at all, but found something that was worth sharing and got me excited… And when I started writing I intended it to be a short post, too.
If you have been digging around Oracle session performance counters a little you undoubtedly noticed how their number has increased with every release, and even with every patch set. Unfortunately I don’t have a 11.1 system (or (more...)
I have recently upgraded my RAC 18.104.22.168.3 system to RAC 22.214.171.124 including the RDBMS installation. Currently I am updating my skills with information relevant to what I would normally have called 12c Release 2 (so that would also answer the question: when is 12c Release 2 coming out?). Then I realised I haven’t posted a first look at RAC 12c post yet-so here it comes.
There are (more...)
This is probably as much a note-to-self as it can possibly be. Recently I have enjoyed some more in-depth research about how the Linux kernel works. To that extent I started fairly low-level. Theoretically speaking, you need to understand the hardware-software interface first before you can understand the upper levels. But in practice you get by with less knowledge. But if you are truly interested in how computers work you might want to consider reading (more...)
Oracle 126.96.36.199 is out, after lots of announcements the product has finally been released. I had just extended my 188.8.131.52.3 cluster to 3 nodes and was about to apply the July PSU when I saw the news. So why not try and upgrade to the brand new thing?
What struck me at first was the list of new features … Oracle’s patching strategy has really changed over time. I (more...)
I had an interesting discussion as part of my latest presentation at the UKOUG RAC CIA & Database Combined SIG. Part of my talk was about the implications of the new threaded execution model in Oracle.
Since “we do not use Windows” (except for gaming) I can’t compare the Windows thread model to the new 12c implementation on UNIX. There are however interesting implications when switching to the new model, some of which I’d like (more...)
Direct NFS is a great feature that I have finally had the time to investigate further. Since I always forget how to set it up and I didn’t find blog posts about this subject elsewhere I decided to put something together.
In this configuration I am using a virtual machine named server1 to export a directory to server2. Oracle is not as lenient as myself and may have certain support requirements when it comes to (more...)
Anyone who has looked at Exadata might ask the question, and I did so too. After all, cell smart table scan is in wait class User IO so there should be more, right? This is what you find for a smart scan:
NAME PARAMETER1 PARAMETER2 PARAMETER3 WAIT_CLASS
------------------------------ -------------------- -------------------- ------------------------------ ---------------
cell smart table scan cellhash# User I/O
cell smart index scan cellhash# User I/O
Compare this to the traditional IO request:
NAME PARAMETER1 PARAMETER2 (more...)
I recently was involved in an investigation on a slow-running report on an Exadata system. This was rather interesting, the raw text file with the query was 33kb in size, and SQL Developer formatted the query to > 1000 lines. There were lots of interesting constructs in the query and the optimiser did its best to make sense of the inline views and various joins.
This almost lead to a different post about the importance (more...)