Linux Engineer - Secure - on-site Hampshire

Job Description:

Role Summary

The ITO Linux Engineer (Level 3) is the Linux technical authority across DXC-managed customer environments, accountable for platform integrity, complex troubleshooting, performance optimisation and architectural improvements for mission-critical workloads. They design, validate and maintain secure OS baselines and oversee patching and vulnerability management to ensure stability, security, performance and audit readiness in regulated environments.

They own major Linux incidents and root-cause analysis, advising on clustering, high availability, disaster recovery configurations, kernel tuning, storage integrations and network dependencies. They automate operations using advanced shell scripting and infrastructure-as-code, approve high-risk changes following review, and mentor junior engineers to build capability and consistency.

Bridging operations and engineering, they support lifecycle planning, platform modernisation and integration with automation, monitoring and configuration management tools. They partner with security and compliance teams to enforce enterprise hardening standards and maintain audit-ready documentation and evidence. The role demands deep technical expertise, architectural judgement and calm, authoritative decision-making under pressure in regulated, mission-critical environments.

Due to the nature of the work and the customers we support, the successful candidate must be eligible to meet UK Government and contractual personnel security requirements, including the applicable residency requirements for the role, and have the right to work in the United Kingdom. Some roles may also be subject to nationality requirements where these are necessary to meet UK Government or contractual security obligations.

Please note the roles will require attendance on-site in Hampshire 5 days a week.

Key Responsibilities

• Lead Linux capacity planning from CPU, memory, disk, I/O, swap and network trends, recommending scaling, consolidation or platform refresh.
• Define and regularly review secure RHEL, CentOS, Oracle Linux and SUSE baselines aligned with CIS, STIGs or equivalent standards.
• Plan patching and vulnerability cycles, including sequencing, risk assessment and rollback, to maintain service continuity within constrained change windows.
• Identify end-of-life distributions, kernels and dependencies and recommend upgrades or migrations to maintain supportability and compliance.
• Maintain accurate Linux CMDB records and configuration management discipline across operations and changes.
• Analyse incidents, performance data and vulnerability scans to identify systemic weaknesses and improvement opportunities.
• Own root-cause analysis for major and recurring incidents, implementing corrective actions and embedding prevention in procedures and baselines.
• Automate repetitive tasks with advanced shell scripting, Ansible, Puppet or equivalent tools to improve consistency, accuracy and efficiency.
• Update runbooks, procedures and knowledge articles with current practice, known errors and lessons learned.
• Evaluate containerisation, immutable infrastructure and infrastructure-as-code, recommending adoption where reliability, security or efficiency improves.
• Lead or support platform modernisation aligned with organisational strategy and industry best practice.
• Advise customers, service delivery, security and compliance stakeholders in service reviews, governance forums and risk discussions.
• Partner with security teams to enforce hardening standards, deliver prioritised vulnerability remediation and maintain audit evidence.
• Coordinate with application, database, network, storage and virtualisation teams on Linux dependencies affecting performance, connectivity and high availability.
• Lead major-incident technical bridges, updating incident managers and stakeholders on root cause, impact and recovery.
• Mentor junior engineers through technical guidance, work reviews, knowledge sharing and structured development.
• Design, validate and maintain secure OS baselines and repeatable, auditable builds that meet regulatory and contractual requirements.
• Review high-risk kernel, clustering, storage and baseline changes, assessing risk and giving technical approval before CAB submission.
• Design, test and document clustering and HA using Pacemaker, Corosync, DRBD, Oracle RAC dependencies and application-level clustering, including failover.
• Design and oversee enterprise storage integration across Fibre Channel, iSCSI, DM-Multipath, NFS and GFS2/OCFS2 shared storage.
• Support OS upgrades, distribution migrations and the transition to automation, monitoring and configuration management tools.
• Maintain build templates, Kickstart/AutoYaST configurations and post-installation automation for consistent, hardened, audit-ready provisioning from first boot.
• Develop Bash/Python scripts, Ansible playbooks, Puppet manifests or equivalent infrastructure-as-code for configuration, compliance, patch orchestration and reporting.
• Configure and validate Fibre Channel SAN, iSCSI, DM-Multipath, NFS and GFS2/OCFS2 storage with appropriate redundancy and failover.
• Tune sysctl, I/O schedulers, hugepages, swappiness, OOM behaviour, ulimits, cgroups and network parameters for mission-critical workloads.
• Integrate monitoring (Nagios, Zabbix, Prometheus, SCOM, SolarWinds or equivalent), logging (rsyslog, ELK, Splunk) and configuration management for estate-wide visibility, alerting and compliance reporting.
• Own major Linux incidents, directing investigation and resolution of kernel panics, cluster failovers, storage path failures, severe performance issues and security incidents.
• Lead post-incident root-cause analysis, producing RCA reports, defining corrective and preventive actions and updating baselines, runbooks and procedures.
• Resolve escalations beyond L2, including performance degradation, kernel faults, clustering/HA failures, multipath issues, authentication, certificates and cross-domain Linux, network, storage and application faults.
• Act as the Linux team’s final escalation point, providing authoritative technical guidance and decisions under pressure.
• Oversee regulated Linux patching and vulnerability cycles, assessing, testing and deploying security errata, kernel updates and configuration fixes within agreed timescales and change processes.
• Review and approve high-risk changes before execution, assessing technical risk, impact and rollback readiness and providing required sign-off.
• Maintain audit-ready compliance reports, patch records, configuration snapshots, RCA reports and change evidence for internal and external reviews.
• Monitor clustering, HA and DR health and performance, validating failover readiness, replication health and quorum status.
• Proactively analyse mission-critical workloads to address bottlenecks and tuning opportunities before service impact.

Required Skills & Experience

Essential

Linux Operations Experience. 5 - 10 years administering and engineering Linux in enterprise, mission-critical or regulated environments, with deep operational and architectural expertise in RHEL, CentOS, Oracle Linux or SUSE and proven ownership of complex outcomes across large production estates.

Advanced Troubleshooting. Expert troubleshooting across kernel, system, networking, storage, file systems, authentication and application dependencies, resolving panics, performance crises, storage failures, split-brain and cross-domain faults through structured RCA and crash, strace, perf, ftrace, SystemTap, tcpdump, blktrace, journalctl, dmesg and sar.

Clustering & High Availability. Deep expertise designing, validating and troubleshooting mission-critical HA using Pacemaker, Corosync, DRBD, fencing/STONITH, quorum management and resource agents, including failover testing and split-brain prevention.

Storage Integration. Expert Linux storage integration and troubleshooting across Fibre Channel SAN, iSCSI, DM-Multipath, NFS and GFS2/OCFS2, covering HBA-to-file-system connectivity, path failures and performance issues.

Kernel Tuning & Performance Optimisation. Advanced workload profiling and bottleneck resolution through sysctl, I/O schedulers, hugepages, swappiness, OOM, NUMA, cgroups, resource limits and network tuning for mission-critical applications.

Security Hardening & Compliance. Experience designing, validating and maintaining CIS/STIG-aligned or equivalent OS baselines, with proficiency in SELinux/AppArmor, FIPS, auditd and vulnerability remediation under contractual compliance and external assurance requirements.

Patching & Vulnerability Management. Experience overseeing regulated Linux patching, including strategy, risk assessment, kernel updates and security errata through Red Hat Satellite, SUSE Manager or equivalent, within agreed timescales and change processes.

Automation & Infrastructure-as-Code. Advanced Bash/Python scripting and Ansible, Puppet, Chef or SaltStack experience to design and implement provisioning, configuration enforcement, compliance checks, patch orchestration and reporting at scale.

Networking. Strong Linux networking knowledge covering bonding/teaming, VLANs, routing, firewalld/nftables, TCP tuning and tcpdump/ss/ip/nmcli troubleshooting, including impacts on applications, storage connectivity and cluster communication.

ITIL Practices. Strong Incident, Problem, Change and Configuration Management knowledge, including major-incident ownership, RCA leadership, high-risk change approval, CMDB accuracy and audit-ready documentation.

Major Incident Ownership. Proven ownership of major Linux incidents, directing cross-team diagnostics and resolution under pressure, producing detailed RCA reports and ensuring corrective action.

Mentoring & Technical Leadership. Experience mentoring junior engineers through technical guidance, work reviews and incident/change coaching, with commitment to developing L2 capability and reducing escalations.

Documentation & Audit Readiness. Ability to maintain accurate, controlled and accessible technical documentation, RCA reports, baseline evidence and compliance artefacts for internal and external audits.

Change Review & Approval. Experience approving high-risk changes through technical risk, impact, dependency and rollback assessments and formal technical sign-off.

Desired:

Certifications. RHCE, RHCA, Red Hat Certified Specialist in High Availability Clustering or Linux Performance Tuning, SUSE Certified Engineer (SCE), or equivalent advanced Linux certification.

ITIL 4 Foundation. ITIL 4 Foundation certification or higher, demonstrating knowledge of ITIL 4 practices and the service value chain.

Containerisation & Orchestration. Docker, Podman, Kubernetes and OpenShift experience covering production Linux engineering, resource management, security and troubleshooting.

Cloud Platforms. Linux administration on AWS EC2, Azure VMs and GCP Compute Engine, including cloud networking, storage, identity integration and operational differences from on-premises workloads.

DR & Resilience. Experience designing and validating Linux disaster recovery, including replication, backups and recovery procedures aligned with RTO/RPO targets.

Monitoring & Observability. Deep Nagios, Zabbix, Prometheus/Grafana, ELK and Splunk experience, including custom checks, alert design and Linux performance dashboards.

Database Platform Awareness. Working knowledge of Oracle, PostgreSQL and MySQL/MariaDB and their Linux configuration, tuning and storage requirements for performance and availability.

CI/CD & DevOps Practices. Familiarity with Linux CI/CD, GitOps and DevOps, including automated testing, pipeline-driven configuration deployment and version-controlled infrastructure.

Platform Modernisation. Experience supporting or leading OS upgrades, distribution migrations, immutable infrastructure adoption and transitions from legacy to modern operational tools.

Compliance & Governance. Awareness of ISO 27001, Cyber Essentials, NIST and JSP 440/604 and their Linux security and audit implications in defence and regulated environments.

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