Marcus W.
Senior IT Open Source Consultant | Linux · Kubernetes · Database Migration (PostgreSQL/MariaDB)
Experience
Oct 2024 - Jul 2025
10 monthsAdministrator, DevOps Engineer
KZVB
- Planned and implemented new network infrastructure (VLAN, LACP, DMZ, structured cabling)
- Migrated from VMware to KVM using Oracle Linux Virtualization Manager (OLVM), including CPU pinning
- Hardened the entire environment using SELinux (KVM hosts, container hosts, database servers)
- Configured and operated the virtualization platform with OLVM and Ansible-based provisioning
- Containerized and redeployed critical services: WordPress, Jenkins, PostgreSQL, MariaDB, Subversion with Apache + AD integration
- Developed Ansible playbooks for automated deployment and configuration management
- Integrated Foreman for repository and security management in the DMZ
- Produced technical documentation in Markdown; organized in Bookstack
- Coordinated with external vendors (e.g. HPE) for hardware installation and setup
- Achieved successful migration from VMware to a fully automated KVM infrastructure, reduced licensing costs, stable containerized services, and comprehensive documentation
Jul 2023 - Oct 2024
1 year 4 monthsDevOps Engineer / IT Consultant / System Administrator
KZVB
- Operated and improved a complex production environment (Ansible, Docker, Kubernetes, Git)
- Administered PostgreSQL and Oracle database instances
- Analyzed and maintained virtualization and storage infrastructure (vSphere, HPE 3PAR, Multipath)
- Delivered onboarding and technical training for internal admins on Ansible, Kubernetes, CI/CD
- Created technical documentation and ensured knowledge transfer
- Integrated Linux servers with the Active Directory domain using SSSD
- Maintained Docker container environments and KVM-based virtual machines
- Refactored and extended Bash and Python scripts
- Corrected and enhanced existing Ansible playbooks
- Conducted workshops and introduced ChatGPT/Gemini for prompt engineering
- Ensured operational stability, improved backup and recovery strategy, and strengthened in-house autonomy through training
Feb 2021 - Oct 2023
2 years 9 monthsDevOps Engineer / Linux Specialist / Database Migration
MLP
- Designed and operated Kubernetes clusters (deployment, Helm, monitoring)
- Managed containerized applications (logging, secrets, persistent volumes, registry integration)
- Migrated live Oracle databases to PostgreSQL using Altova MapForce, Python, and pgloader
- Set up a highly available PostgreSQL environment with streaming replication and VIP failover (keepalived)
- Developed automation scripts for data migration and verification (Python, Bash)
- Administered mixed Linux platforms (SLES, Ubuntu, RHEL)
- Successfully transitioned multiple applications to Kubernetes, unified database landscape, and established documented high-availability processes
Dec 2019 - Jul 2021
1 year 8 monthsDevOps Engineer · Linux Administrator
Univention
- Designed and implemented a Samba-compatible Active Directory domain with Univention Corporate Server (UCS)
- Integrated UCS into existing Linux and Windows environments
- Developed Python automation scripts for user provisioning, ACLs, and backups
- Documented the domain architecture and created handover procedures
- Provided consulting on LDAP/Kerberos-based application integration
- Delivered a robust, maintainable authentication infrastructure with seamless mixed-platform integration
Jun 2017 - Dec 2021
4 years 7 monthsAdministrator, XSD Designer, Data Analyst
Rheinmetall
- Designed and documented complex XML/XSD target structures
- Created reusable and configurable mapping templates in Altova MapForce
- Implemented multi-stage mappings: Oracle → XML → JSON
- Automated mapping processes via MapForce scripts and job scheduling
- Integrated schema validation and test datasets
- Optimized performance for large data volumes and repeated runs
- Successfully migrated large datasets including delta updates, delivered audit-proof documentation, and enabled integration across diverse systems
Jan 2008 - Present
17 years 8 monthsIT Project Manager · System Administrator
Comelio GmbH
- Planned, set up, and operate a fully self-hosted data center with fibre uplink and static IPs
- Virtualized infrastructure using KVM (virsh) and Ceph block storage with multipath connectivity
- Deployed and operated a Kubernetes platform for containerized services
- Dockerized core services: Bookstack, Nextcloud, OpenProject, Mailcow
- Built and secured firewall/VPN infrastructure with OPNsense and WireGuard
- Integrated a Samba-based AD domain with Kerberos and SSSD for Linux systems
- Implemented a browser-based training system via Apache Guacamole with snapshots and file transfer
- Rebuilt and hosted company websites with WordPress on private infrastructure
- Used AI tools (ChatGPT/Gemini) for documentation, automation, and operational support
- Achieved stable 24/7 availability, scalable training labs, full cloud-independence, and well-documented self-hosting architecture
Summary
I support companies in building digital infrastructures that are self-determined, maintainable, and future-proof – based entirely on open-source technologies and independent of proprietary ecosystems. I place strong emphasis on knowledge transfer through structured documentation and hands-on training.
I take a holistic view of IT – from the network layer to container platforms to stable applications. For refining language, exploring edge cases, and reflecting on architectural choices, I occasionally use supportive tools like ChatGPT and Gemini – for structure, phrasing, best-practice input, and, admittedly, sometimes a bit of emotional support during long working phases. All decisions, content, and technical solutions, however, are based entirely on my own expertise and experience.
Languages
German
NativeEnglish
AdvancedEducation
Ruhr University Bochum
Electrical Engineering & Computer Science · Bochum, Germany
Certifications & licenses
CKA – Certified Kubernetes Administrator
CKAD – Certified Kubernetes Application Developer
CKS – Certified Kubernetes Security Specialist
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