Sergio Barrientos - AI Infrastructure Engineer

Professional Summary

Linux and AI Infrastructure Engineer with 3+ years operating 300+ RHEL servers in a BaFin/ECB-regulated banking environment. Specialized in RHEL modernization, Ansible automation, and enterprise platform operations across VMware vSphere and cloud. Deep practical experience deploying and tuning generative AI systems locally — llama.cpp, GGUF runtime optimization, ROCm GPU compute, and edge inference on RK3588. Proven ability to communicate complex infrastructure and AI concepts across technical and non-technical stakeholders, including enterprise PMs and business leaders. Combines production-grade Linux operations with hands-on GenAI prototyping and solution design.

Work Experience

Linux and Virtualization Engineer | Deutsche Pfandbriefbank AG

Jul 2025 - Present

Full-time | Hybrid | Madrid, Spain | BaFin/ECB-supervised bank | 300+ Linux servers

Platform ownership: Part of the Linux infrastructure team operating 300+ RHEL servers across multiple datacenters for banking-critical workloads. Act as the go-to technical resource for infrastructure questions, bridging Linux operations with application-layer concerns.
RHEL modernization: Leading phased RHEL 7/8 to 9 migration with Satellite-based provisioning, patching, and compliance controls while maintaining service continuity — end-to-end lifecycle management from assessment to production.
Automation: Built Ansible and Git workflows for provisioning, patching, and configuration drift remediation, replacing manual runbooks with auditable, peer-reviewed infrastructure-as-code.
Operations: Running HA and DR activities across VMware vSphere and application platforms including Nginx, Apache, Tomcat, JBoss, and PostgreSQL. Hands-on troubleshooting across the full stack.
GenAI delivery: Delivering Azure AI Foundry use cases for enterprise document extraction and internal process automation. Designing production-ready architectures for LLM-based solutions, from prompt engineering to API integration and monitoring.
Cross-functional collaboration: Recognized by project PMs as the technical translator who can explain complex infrastructure decisions to non-technical stakeholders, enabling smoother project governance and faster decision-making.

Linux Red Hat Specialist / IT Application Specialist | Sopra Steria

Nov 2023 - Jul 2025

Full-time | Hybrid | Madrid, Spain | Railway sector client | 100+ servers

Technical coordination: Coordinated a 5-person team for maintenance, patching, and support of a critical application across 100+ Linux and Windows servers at Bane NOR, Norway's national railway operator, consistently meeting SLA targets.
Systems automation: Maintained RHEL compliance with Satellite and built Ansible automation that reduced deployment effort from hours to minutes — measurable efficiency gains delivered in a regulated sector.
Virtualization: Managed VMware vSphere and vCenter operations, VM lifecycle tasks, and resource optimization across cloud and on-prem environments.
Enterprise operations: Handled ServiceNow incident/change flows and Active Directory plus Kerberos integration for Linux systems. Full ITIL-aligned operational discipline.

IT Application Specialist | Sopra Steria

Apr 2023 - Jan 2025

Full-time | Madrid, Spain | Multi-technology enterprise support

Provided enterprise support across Linux, Windows, and cloud environments, building the operational foundation later applied in Linux platform engineering and AI infrastructure roles.

Internship Trainee | Sopra Steria

Apr 2023 - Jun 2023

Internship | Madrid, Spain

Built early experience in incident handling, directory services, and ITIL-oriented enterprise support workflows.

Technical Skills

Linux / RHEL RHEL 7/8/9, Red Hat Satellite, LVM, systemd, SELinux, Kickstart, HA/DR, performance tuning Automation / IaC Ansible, Bash scripting, Git workflows, CI/CD pipelines, infrastructure as code AI Infrastructure llama.cpp, GGUF quantization, ROCm GPU compute (AMD), RK3588 edge inference, KV-cache tuning, local LLM benchmarking, RAG workflows, Azure AI Foundry Platforms / Services VMware vSphere/vCenter, Nginx, Apache HTTP Server, Tomcat, JBoss Web Server, PostgreSQL, SSL/TLS Cloud / GenAI Microsoft Azure, Azure AI Foundry, Document Intelligence, LLM prototyping, solution architecture Operations CheckMK, ServiceNow, Active Directory, Kerberos integration, ITIL, change management

Selected AI Projects

llamacpp-workbench: Built and published a remote llama.cpp workbench for GGUF models with model management, runtime and KV-cache tuning, streaming chat, and benchmark-backed RK3588 profiles.
Applied AI portfolio: Documented real implementation work across Azure AI Foundry, document intelligence, local inference, and performance tuning on constrained hardware — 40+ case studies at sergiiob.dev.

Certifications & Education

RHCSA - Red Hat Certified System Administrator Sep 2024

RHCE - Red Hat Certified Engineer In progress — target 2026

Technician in Computer Systems and Networks Administration Jun 2023 | Madrid, Spain

Languages

Spanish: Native English: Professional working proficiency French: Basic

Portfolio

sergiiob.dev - Engineering portfolio with 40+ structured case studies on infrastructure automation, RHEL lifecycle management, platform operations, local AI engineering, and applied AI delivery.