My name is Sergio Barrientos. I am a Linux systems administrator and virtualization engineer based in Madrid, and this page is a brief introduction to my background and the kind of work I do.
Currently I am part of the infrastructure team at Deutsche Pfandbriefbank, a European bank regulated under BaFin and the ECB. We manage over 300 Red Hat Enterprise Linux servers across multiple datacenters, and my responsibilities cover the full server lifecycle: provisioning through Red Hat Satellite, large-scale patching coordination, ongoing RHEL 9 migrations, and general platform reliability. Working in a strictly regulated banking environment means every change is documented, reviewed, and fully auditable.
Improving operational efficiency through automation has been a consistent focus throughout my career. Using Ansible and Git I have built version-controlled infrastructure workflows that replaced unreliable manual processes with repeatable, peer-reviewed code. I also work regularly at the application layer managing platforms such as Nginx, Apache, Tomcat, JBoss, and PostgreSQL, covering everything from reverse proxy configuration and SSL management to deployment troubleshooting and database tuning.
Before joining pbb, I led a small technical team at Sopra Steria supporting a Norwegian financial client across mixed Linux and Windows environments, with all communication in English. That experience strengthened both my technical range and my ability to manage delivery alongside a team.
Outside my main role I dedicate a significant amount of time to applied AI, working with Azure AI Foundry to build document intelligence pipelines and experimenting with local language models. I document this work alongside infrastructure solutions on my website sergiiob.dev, which now has over 40 technical posts based on real problems I have encountered and solved.
I currently hold the RHCSA certification and am actively preparing for the RHCE. I am also comfortable working with VMware vSphere, Active Directory and Kerberos integrations, and ServiceNow workflows. This portfolio is a practical showcase of how I work and what I build.
Sergio Barrientos