Lead Engineer – Unix Infrastructure (Linux & AIX) at Regent

REGENT LP Regent is a global private holding company focused on investing in and transforming businesses across a broad spectrum of industries including automotive, technology, consumer products, retail, industrial, and media. Known for driving innovation and operational excellence, Regent partners with management teams to unlock long-term value. We are seeking a Network Engineer to join one of our portfolio companies, based in Krakow. ROLE OVERVIEW We are seeking an experienced Lead Engineer specialising in Unix Infrastructure to join a global technology team. This area lead role carries full accountability for the stability, security, and continuous improvement of a Linux and AIX server estate - spanning on-premises data centres, VMware virtualisation, IBM PowerVM, and VMC on AWS. The Lead Engineer is responsible for managing the lifecycle of Unix servers, ensuring the stability, security, and performance of business-critical applications. The successful candidate will bring deep Unix expertise alongside the leadership capability to mentor junior team members, drive continuous improvement, and collaborate across application, network, storage, and cloud teams.* *Please note this role is on-site 5 days per week AREA CONTEXT The Unix area is dedicated to the management of server operating systems, ensuring the stability, security, and performance of business-critical applications. It covers the deployment, patching, and monitoring of Unix (Linux, AIX) servers across data centres and cloud environments. The area addresses operational challenges such as end-of-life hardware, legacy systems, and the need for rapid response to incidents. It supports business continuity through robust backup and recovery processes and aligns with best practices for system administration. KEY RESPONSIBILITIES • Build, provision, and maintain Linux (RHEL/CentOS/Ubuntu) and AIX servers, including domain/LDAP integration, security baseline enforcement, and CIS hardening. • Execute patching cycles using yum/dnf (Linux) and SUMA/NIM (AIX); validate application services post-patch and record evidence for compliance. • Monitor OS and VM health (syslog, journal, AIX errpt, performance counters) and resolve faults; implement and tune monitoring thresholds and dashboards to reduce alert noise. • Troubleshoot identity integration (SSSD, PAM, Kerberos), SSH key issues, and name resolution; investigate CPU, memory, I/O, and network performance bottlenecks using sar, iostat, vmstat, and nmon. • Manage TLS/certificate bindings for Unix-hosted services; enforce least-privilege access, SSH key lifecycle controls, and secure service account usage. • Ensure antivirus/EDR agents are installed, healthy, and reporting across the Linux/AIX estate; remediate coverage gaps in line with security policy. • Manage and administer Rubrik (the primary backup solution) across the Unix estate: maintain backup agents, validate policy coverage, and run periodic restore tests; capture and document DR evidence; participate in DR tests (site failover, recovery) and document outcomes. • Track EOL OS and hardware versions; plan and coordinate in-place upgrades or platform migrations, managing risk with application and business stakeholders. • Lead incident response and root-cause analysis for Unix server-related issues; drive lasting remediation and produce post-incident reports. • Oversee, maintain, and support the Hypervisor/Virtualisation layer for Unix workloads (VMware vSphere/ESXi and IBM PowerVM/LPAR) across on-premises data centres and VMC on AWS. • Maintain and support Unix HA Clusters across on-premises data centres (HACMP/PowerHA on AIX; Pacemaker/Corosync on Linux), both on-premises and in VMC on AWS. • Support application teams with prerequisites, port configurations, NFS/storage dependencies, and service integrations; collaborate with network, storage, and cloud teams. • Keep server runbooks, diagrams, and CMDB attributes current and accurate; maintain comprehensive documentation of architectures, configurations, and identity integrations. • Provide weekly operational KPIs (availability, incidents, patch compliance, backup success) and present findings in governance, reporting, and service review meetings. • Ensure alignment with SLA requirements; lead the response to audit findings, ensuring timely remediation and evidenced closure. • Manage vendor relationships and coordinate with third-party Unix support providers (IBM, Red Hat, hardware OEMs); oversee secure decommissioning of EOL hardware. • Mentor and develop engineers, fostering skill development and knowledge sharing; manage team workload and capacity across concurrent workstreams, maintain and prioritise the team's Jira ticket queue, and organise the On-Call rota for the Unix area. • Drive continuous improvement in Unix server management processes and stay current with Linux and AIX technology roadmaps and emerging best practices. • Support business continuity and disaster recovery planning for Unix server environments. QUALIFICATIONS Experience • 7+ years of enterprise Linux and/or AIX administration and engineering, with at least 2 years in a team lead or managerial role: including team workload management, ticket queue prioritisation (Jira), and hands-on development of engineers. • Demonstrated experience managing large-scale Unix estates across hybrid on-premises and cloud environments, covering RHEL/CentOS/Ubuntu and IBM AIX. • Hands-on experience with VMware vSphere/ESXi (for Linux workloads) and IBM PowerVM/LPAR (for AIX), including HA cluster management (HACMP/PowerHA, Pacemaker). • Proven track record delivering complex Unix OS migrations, EOL remediations, and platform consolidation projects on time and within risk tolerance. • Deep experience with Linux/AIX identity integration: SSSD, PAM module configuration, Kerberos realm binding, LDAP/AD integration, and SSH key lifecycle management. • Hands-on experience with patch orchestration on both Linux (yum/dnf, Red Hat Satellite) and AIX (SUMA/NIM), including troubleshooting failed updates at scale. • Familiarity with TLS/PKI infrastructure for Unix-hosted services and certificate lifecycle management. • Background supporting or leading audit and compliance activities (ISO 27001, SOC 2, PCI-DSS, or equivalent) with evidenced remediation. • Proficiency with ITSM and project tracking platforms — Jira (primary) and ServiceNow or equivalent — for incident management, ticket queue management, CMDB, and change control. Technical Skillset • Linux & AIX server administration: OS installation, hardening (CIS benchmarks), kernel tuning, SELinux/AppArmor policy, and package management (yum/dnf, RPM, AIX filesets). • Virtualisation layer administration: VMware vSphere/ESXi for Linux workloads and IBM PowerVM/LPAR for AIX — including LPAR sizing, shared processor pools, and capacity planning. • Patch management tooling for Linux (yum/dnf, Red Hat Satellite) and AIX (SUMA/NIM); troubleshooting of failed updates and prerequisite management. • Linux/AIX identity integration: SSSD, PAM configuration, Kerberos realm setup, LDAP/AD binding, and SSH key lifecycle management at scale. • Performance analysis and triage: sar, iostat, vmstat, top, AIX nmon, IOPS profiling, and kernel parameter tuning. • EDR/AV agent operations: health monitoring, coverage gap remediation, and security policy alignment (CrowdStrike Falcon, Qualys, or equivalent). • Backup and disaster recovery: Rubrik (primary backup platform) administration, agent management, restore testing, HACMP/Pacemaker failover testing, and evidence capture; familiarity with Veeam or IBM Spectrum Protect is an advantage. • EOL remediation: in-place OS upgrade planning, P2V migration coordination, application re-platforming, and hardware decommissioning. • CMDB/ITSM proficiency: Jira for team ticket queue management and workload tracking; runbook maintenance, diagram upkeep, and accurate CMDB attribute management (ServiceNow or equivalent). • Scripting and automation: Bash, Python, and/or Ansible for operational tasks, compliance reporting, and infrastructure-as-code patterns; experience developing AI-assisted automation or autonomous agents to accelerate infrastructure operations is a strong advantage. • Mentoring and developing engineers in Unix server operations and troubleshooting methodology; team workload management and Jira ticket queue prioritisation. • AI-assisted automation and agent development (advantageous): ability to work with AI tooling and develop autonomous agents to accelerate Unix infrastructure operations; candidates with hands-on experience building AI agents or integrating LLM-based automation into infrastructure workflows will be strongly preferred.