Monthly Archives: June 2013

“Cannot allocate memory” error when starting a Xen guest

When trying to start a Xen guest, having plenty of primary memory I got the following error message: Error starting domain: POST operation failed: xend_post: error from xen daemon: (xend.err “Error creating domain: (12, ‘Cannot allocate memory’)”) In this case it was very useful comparing the assigned memory of the Domain-0 (which “contains” all the […]

Progreso de los objetivos de la Agenda Digital para Europa 2020

101 acciones y 7 pilares definen la estrategia de la Agenda Digital para Europa (DAE, Digital Agenda for Europe) dentro de la iniciativa Europa 2020, cuya ciclópea tarea es reactivar la economía de la Unión Europea exprimiendo al máximo las tecnologías digitales. Para poder revisar de forma cuantificable su progreso, la DAE definió 13 objetivos […]

Reaching the open files limit of a Qpid server with simple Nmap requests

I recently noticed a curious behavior of Apache Qpid Messaging server 0.20 while performing some simple nmap checks: while true; do   echo “$(date +’%Y/%m/%d-%H:%M:%S’) $(nmap -p 5672 qpid_server | grep ‘^5672\/tcp’)”   sleep 0.5 done Qpid’s log started growing very fast and very soon it was flooded with many (really, many: hundreds of thousands) lines […]

Using sudo with NRPE requests

I want to receive an alert whenever root’s crontab of a machine has been updated. In RHEL (Red Hat Enterprise Linux) 6 the crontab is stored in /var/spool/cron/root and it is only readable/writable for root itself. After installing the required yum packages (examples: nagios-plugins-all, nagios-plugins-nrpe, nrpe) you can begin this implementation by checking if the […]