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August 2012

Lessons from Africa, Part 2

Last week was busy… making travel arrangements for this week’s trip to New York (technically Jersey) and some light analysis of AWR reports from exadata RAT runs and some heavy troubleshooting of a Solaris x86 RAC cluster with random node reboots. (I think I finally traced the node reboots to a kernel CPU/scheduling problem). I really did thoroughly enjoy my time in Africa despite being nowhere near Oracle software – but it feels good to be working on challenging cluster problems again!

Lessons from Africa, Part 2

Last week was busy… making travel arrangements for this week’s trip to New York (technically Jersey) and some light analysis of AWR reports from exadata RAT runs and some heavy troubleshooting of a Solaris x86 RAC cluster with random node reboots. (I think I finally traced the node reboots to a kernel CPU/scheduling problem). I really did thoroughly enjoy my time in Africa despite being nowhere near Oracle software – but it feels good to be working on challenging cluster problems again!

Nexus 7 : Impressions after a couple of days…

It’s been a couple of days since I got my spangly new Nexus 7. I was hoping to chalk it down to an impulse buy, but after 3 failed attempts to buy one at high-street stores I got frustrated and ordered one off Google Play directly…

Parallel Execution Analysis Using ASH - The XPLAN_ASH Tool

Preface

Note: This blog post actually serves three purposes:

  1. It introduces and describes my latest contribution to the Oracle Community,  the "XPLAN_ASH" tool

  • It accompanies a future OTN article on Parallel Execution that will be published some time in the future

  • It is supposed to act as a teaser for my upcoming "Parallel Execution Masterclass" that will be organized by Oracle University and can be booked later this year
  • Table Of Contents

    Introduction

    Real-Time SQL Monitoring Overview

    Real-Time SQL Monitoring Shortcomings

    Adventures with Dropbox and KeePass…

    Thanks to Eddie Awad, I’ve been using 2-step verification on my Google account for a while. Now Jake from The Appslab has scared me into using a password manager and revamping all my passwords…

    We use KeePass (on Windows) at work to hold all our passwords, so I figured I’d go with that and see how I get on. Unlike work, I want to use a single store for all my devices, so I finally found a use for my Dropbox account.

    Dropbox Installations

    If you don’t already have it, you need to install Dropbox on your device(s). For mobiles, that means their respective app stores. For computers (Linux, Mac and Windows), you can get it from the Dropbox website.

    Shared KeePass Installation

    Using LVM snapshots for backup and restore of filesystems

    This post really is about using LVM (Logical Volume Manager; an abstraction layer for disk devices) snapshots. A snapshot is a frozen image of a logical volume, which simply means “filesystem”. It’s not really “frozen”, LVM2 snapshots are read/write by default. But you can freeze a filesystem in time with a LVM snapshot.

    The background of this really is Exadata (computing node) and upgrading, but has nothing unique to Exadata. So don’t let this bother you. But the idea of using LVM snapshots popped up when dealing with Exadata computing nodes and upgrades.

    First of all: LVM is in development, which mean different Linux versions have different LVM options available to them. I am using the Exadata X2 Linux version: RHEL/OL 5u7 x86_64. I guess OL6 has more and more advanced features inside LVM, but with X2, OL5u7 is what I have to use. So the steps in this blogpost are done with this version. Any comments are welcome!

    Making SQL Performance Solutions Stick Webinar - August 29

    Join me for the 2nd Embarcadero Community webinar in my Performance Series on August 29 entitled "Making SQL Performance Solutions Stick". Registration is now open and I'd love to see you there!

    Don't worry if you didn't attend the first session in July. This session will have plenty of new information and does not have any dependency on having to attend the first event.

    I'll be talking about:

    Friday Afternoon

    This is known in the DBA trade as being “in the brown stuff”

    Friday Philosophy – I Am An Exadata Expert

    (Can I feel the angry fuming and dagger looks coming from certain quarters now?)

    I am an Exadata Expert.

    I must be! – I have logged onto an Exadata quarter rack and selected sysdate from Dual.

    The pity is that, from some of the email threads and conversations I have had with people over the last 12 months, this is more real-world experience than some people I have heard of who are offering consultancy services. It’s also more experience than some people I have actually met, who have extolled their knowledge of Exadata – which is based solely on the presentations by Oracle sales people looking at the data sheets from 10,000 feet up and claiming it will solve world hunger.

    Heck, hang the modesty – I am actually an Exadata Guru!

    Event 10046 – Full List of Levels

    Extended SQL trace (a.k.a. debugging event 10046 at a level higher than 1) is one of the key features provided by Oracle to troubleshoot applications using Oracle Database. For many years the available levels were always the same (4, 8 and 12). In fact, since I wrote my first paper about it in May 2000 and the release of 11g nothing changed.

    With 11g, as I described in this post, new levels (16 and 32) were introduced.