linux

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

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!

It has been nine months since I’ve written here. Needless to say, a lot has happened!

First, my family was living in Africa for three months earlier this year while I did some tech work at an NGO hospital. Second, upon our return I decided to join the good people at Pythian. I’m not moving to Canada, although I will travel a decent bit as part of the company’s consulting group.

If you’re interested in the Africa trip, look at the Africa page. I wasn’t working with Oracle technology but it was still a very interesting, challenging and engaging project.

I thought I’d briefly share a few high-level insights. You might be surprised how well these lessons apply almost anywhere (even Oracle-related projects)!

Four Lessons from IT in Rural Africa

1. Understand the Fundamentals

Followers of the blog will know I’ve been using Fedora as my main desktop/server OS for quite some time. I tend to use the default settings as much as possible, so that meant I switched to GNOME3 (when graphics cards allowed) and was generally not too displeased with it. I know a lot of people hate GNOME3, but I found it OK…

I think using XP at work has made me appreciate the simplicity of the old-style menus, so in a little fit of “I need a change”, I switched my window manager to Xfce. It’s quick and kinda basic as far as the interface goes, but feels really comfortable and familiar. So as not to get withdrawal symptoms from all things spangly, I’ve installed Cairo-Doc to get a posh little OSX-like doc at the bottom of my screen.

I’m not sure how long this new look will last, but so far I dig it.

Cheers

Tim…

When you use Oracle ASM (Automatic Storage Management) for your database, the permissions on the block devices on the operating system layer which are used by ASM need to be changed. To be more precise, the owner and group need to be set to ‘oracle’ and ‘dba’ (Oracle documentation) in my case.

I used to do this in a very lazy way, using a simple ‘/bin/chown oracle.dba /dev/sdb’ in /etc/rc.local. This worked for me with RHEL/OL version 5. This has changed with RHEL/OL 6, because the system V startup system has changed to ‘upstart’. Also, the disk devices change ownership back in OL6 if you set it by hand to oracle.dba.

Some of you might have experimented with, or used Oprofile, ltrace/strace, Systemtap, and wished you could look further into the userland process, like dtrace does, because dtrace allows you to profile and look into a process’ function calls.

If you’ve used oprofile/strace/systemtap/etc., you probably found out you can see all the kernel functions which are processed, but it does not get into userspace, or with very limited information. Perhaps the only tool which is different is gdb, which enables you to see userspace function names, but gdb is not a profiler, it’s a debugger. And it works best with (I assume it made for) debugging symbols in the executable. Most (all I presume) commercial executables, like the oracle database executable, do not have debugging symbols.

I didn’t really have a lot of exposure to block-level replication on the storage level before an engagement in the banking industry. I’m an Oracle DBA, and I always thought: why would I want to use anything but Oracle technology for replicating my data from one data centre to another? I need to be in control! I want to see what’s happening. Why would I prefer storage replication over Data Guard?

In an attempt to delay packing for my trip, I decided to give the server installation on Linux a go.

• Oracle WebLogic Server (WLS) 11gR1 (10.3.5) Installation on Oracle Linux 5 and 6
• Oracle Forms and Reports 11gR2 Installation on Oracle Linux 5

The installation was pretty straight forward. I will take a look at some of the further configuration stuff when I get back from my trip.

Cheers

Tim…

This is pretty much a note to myself on how to set up Data Guard broker for RAC 11.2.0.2+. The tests have been performed on Oracle Linux 5.5 with the Red Hat Kernel. Oracle was 11.2.0.2. Sadly my lab server didn’t support more than 2 RAC nodes, so everything has been done on the same cluster. It shouldn’t make a difference though. If it does, please let me know).

WARNING: there are some rather deep changes to the cluster here, be sure to have proper change control around making such amendments as it can cause outages! Nuff said.

Every now and then I am asked about the availability of the presentations I have delivered. Recently somebody asked about a presentation I delivered at the OUG Scotland about multiblock reads, and I promised to make it available. I’ve now uploaded a PDF version of all my old presentations them and put them in the ‘Whitepapers and presentation’ section.

Enjoy!