Martin's Technique Blog

Change of behaviour when setting job_queue_processes=0 in Oracle RDBMS

Martin Wunderli — Tue, 20 Jul 2010 13:08:00 GMT

Hi,

I recently run accross an annoying problem at a customer. We discovered that object statistics were not collected although it was a freshly created 11.2 database (and so we expected default behaviour). When the customer DBA pointed out, that job_queue_processes was set to 0 I replied 'Naaaa, this has nothing to do with scheduler jobs...' Well experience can trick you!

After a lot of tests and a service request at Oracle, we can now say the following: Starting with 11.2 (and not with 11.1!), setting job_queue_processes to 0 will also disable scheduler jobs (both your own and Oracle's). According to Oracle support, this is expected behaviour and 'just' a documentation bug .

Cheers
Martin

Oracle 11gR2 backups to tape with RMAN and Netbackup

Martin Wunderli — Wed, 16 Dec 2009 07:49:00 GMT

Short answer: Currently a no-go, e.g. on Linux. Symantec told my customer to expect a new version of their libobk in Q1/2010. Until then, backups have to be made to disk and then saved with bpbackup (the Symantec CLI util for netbackup) to tape.

Luckily my customer already used our TVD-Backup suite (sorry, german description) which is perfectly capable of just doing this (among a lot of other wonderful things ) and relieving the DBA from writing scripts for this task (incl. space management etc.).

Maybe you have a look...

Martin

Standardized operation across OSes and other borders

Martin Wunderli — Thu, 19 Nov 2009 12:26:00 GMT

Today I gave my talk on standardized operation (e.g. how to operate MySQL as we are used to with Oracle RDBMS) at the DOAG conference in Nuremberg, a talk largely based on the concepts of TVD-BasEnv.You can find it soon here. The talk was well received, and I was quite pleased how big the interest in TVD-BasEnv for MySQL was. Maybe Oracle's takeover of SUN has a positive impact on MySQL, not a negative one, as many fear.

Some general comments on the conference: Very spacious conference center, some quite good talks, good organisation. Worth being there.

Replace Firefox 3 by Firefox 2 in Ubuntu 8.04 Hardy Heron

Martin Wunderli — Sat, 31 May 2008 07:49:00 GMT

Hi,

Firefox 3 in Ubuntu Heron gave me quite some trouble, especially with our SSL-VPN and Tab Mix Plus Add-On: Both do not work. So I decied to go back to Firefox 2. Here is how I did it:

Completely remove Firefox

sudo apt-get remove --purge firefox firefox-3.0 firefox-3.0-gnome-support firefox-gnome-support

Install Firefox 2

sudo apt-get install firefox-2

Create link to make all programs happy which call firefox

sudo ln -s /usr/bin/firefox-2 /usr/bin/firefox

As you can see, I more like to do it on the command line than in the GUI...

Cheers

Martin

Oracle Critical Patch Update October 2007 on RAC

Martin Wunderli — Wed, 31 Oct 2007 09:41:00 GMT

Hi,

Since all molecules of the CPU October 2007 are marked as 'online applicable' to RAC
(nice wording, it means a rolling upgrade is possible, not that all instances stay
online during the patch...), I decided to test it. Clusterware did not have to be
patched, by the way.

Rolling upgrade worked, so far so good. During the whole process, users could work.
However, two big issues - which are not related to this specific CPU, but to the way
Oracle describes the patch process in case of RAC - came up.

First, shutdown transactional local does not wait for a transaction to commit or
rollback if the corresponding session was established via Oracle Net and a srvctl generated service name.
Quite common, not to say standard, in a RAC environment. Some tests revealed that in
case of local connects or Oracle Net connects via SID, the shutdown waited as it
should. The solution was to shutdown the listener of the instance to be patched, to issue

alter system disconnect session 'SID,SERIAL#' post_transaction;

for all sessions, wait until they failover and then issue shutdown. Not very
comfortable but it works.

The second issue was on the VIP. Oracle recommends to issue

srvctl stop nodeapps -n NODE_TO_BE_PATCHED

This, however, also stops the VIP and does NOT failover it to another node. Which
results in TCP timeouts for new connects and failovers (sessions seem to hang). The
solution here is to explicitly start the VIP on a fully available node, e.g. with

crs_start ora.NODE_TO_BE_PATCHED.vip -c FULLY_AVAILABLE_NODE

Remote access with GUI

Martin Wunderli — Sat, 08 Sep 2007 07:15:00 GMT

For quite a while I have been an enthusiastic fan of VNC (better: tightvnc) when it comes to access a remote server including graphics. However, since the VNC variant used in my Laptop OS Ubuntu Dapper (and therefore the OS of the PCs of my wife, father, mother... :-) ) is quite slow, I was looking for alternatives.

I found one with the NX products from http://www.nomachine.com which allow me not to just start a graphical session on a remote machine (via a possibly slow line), but also attach to an existing session on the remote machine (even the graphical root window) or disconnect/reconnect to a session. There are free variants for Linux and Solaris available, unfortunately not for Windows, but VNC server or rdesktop (RDP) are ok in that case.

The most amazing experience for me was the installation. Klick on the download button and let your package manager (the debian one in my case) do the rest. Since the complete login and traffic works through ssh, no extra tunnel in a firewall etc. must be opened. An existing ssh based access infrastructure can be used.

There is also a fully GPL-ed variant called FreeNX which lacks some features like reconnecting etc.