H's Blog

Precise Pangolin

Holger — Thu, 26 Apr 2012 22:37:18 +0000

The next LTS release of Ubuntu is ready for download.

I really like the long-term releases, even more, if they are so fresh, that they provide the latest packages.

SNMP Warnings in Debian Squeeze

Holger — Thu, 19 Apr 2012 21:16:02 +0000

The default installation of snmpd in Debian Squeeze will put several warnings into the daemon.log.

The reason is the licensing of the MIB files, that is not compatible with Debian.

If you are not satisfied with errors on each restart of the snmpd, here are the steps, that solved this problem in my case:

Edit /etc/apt/sources.list and append contrib and non-free to the standard repositories.
apt-get update
apt-get install snmpd snmp-mibs-downloader
Edit /etc/default/snmpd:
export MIBS=/usr/share/mibs/netsnmp/UCD-SNMP-MIB

Commenting the original line export MIBS= did not help, also the definition export MIBS=/usr/share/mibs/netsnmp did not work, so I will leave the MIBS reference in the configuration on UCD-SNMP_MIB.

MySQL Query Log

Holger — Wed, 11 Apr 2012 21:55:30 +0000

If you need details about whats going on within your MySQL instance, the query log is still very useful, even though it's not good for permanent use, since it costs performance and disk space.

But with some luck you already have release 5.1 or later and you can activate the query log on the fly:

Log in to your MySQL instance, e.g. mysql --defaults-file=/etc/mysql/debian.cnf, if you are using a standard MySQL installation on Debian/Ubuntu.
Set the log target: set global general_log_file='/var/tmp/mysql.log'
Activate the log file: set global general_log=1
You can end the logging (and you should really restrict the logging on production systems) with: set global general_log=0

Java VisualVM

Holger — Tue, 10 Apr 2012 22:28:04 +0000

For quick analysis of the options and health of a Java VM I used the jconsole tool, that is part of the Java SDK.

Now there is also VisualVM, that not only provides information about the options and health (CPU, Memory), but also a useful overview of the threads including their state and finally easy access to CPU and memory profiling.

See http://visualvm.java.net/ for details. To start this tool use the command jvisualvm instead of jconsole and select the Java VM that is your object.

Alfresco eats Memory – Yum, Yum

Holger — Sat, 10 Mar 2012 23:18:46 +0000

I recently tried to optimize an Alfresco 4 installation in a 1GB Ubuntu VM and reduction of the default 512m for MaxPermSize was too much, the Tomcat instance goes down after startup and first call to /alfresco.

Considering the remaining memory for the PostgreSQL database, OpenOffice and the operating system, I thought about reduction of Heap and PermSize limits for the Tomcat instance included in the Alfresco installation. Setting the Heap Maximum to 512m instead of 1024m was not the problem, but using 128m for MaxPermSize instead of the 512m killed the instance after the first call to /alfresco.

So better don't touch MaxPermSize in tomcat/scripts/ctl.sh.

Also 1GB of RAM is not recommended for an Afresco VM, better start with 2GB of RAM. The startup of Alfresco currently takes up to 4-5 minutes, shutdown is not faster, which makes reboots of the VM taking 10 minutes even though the VM is restarted within seconds, it's the Alfresco that gives the delay.