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  • Interesting observation about standby redo logs in Data Guard

    Some of you might have followed the discussion around the number of standby redo logs on twitter, but since 140 characters are woefully short for the complete story here’s the writeup that prompted the question. This is a test with 12.1.0.2 on virtualised Linux, repeated on a proper platform with physical hardware. UPDATE: This is…

  • Can you have high redundancy files in a normal redundancy diskgroup?

    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,…

  • Intra-Database IORM in action

    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…

  • A brief history of time^H^H Oracle session statistics

    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…

  • A first look at RAC 12c (part I)

    I have recently upgraded my RAC 12.1.0.1.3 system to RAC 12.1.0.2 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…

  • How to get insights into the Linux Kernel

    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…

  • Upgrading clustered Grid Infrastructure to 12.1.0.2 from 12.1.0.1.3

    Oracle 12.1.0.2 is out, after lots of announcements the product has finally been released. I had just extended my 12.1.0.1.3 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…

  • Implications of threaded_execution = true in 12c

    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…

  • Setting up Direct NFS on Oracle 12c

    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…

  • Why is P1 the only parameter populated in cell smart table scan?

    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: Compare this to the traditional IO request: At first I didn’t understand as to why…