Senior Infrastructure Systems Administrator

Location: Lisle, IL / Chicago‑area preferred
Work Arrangement: Hybrid / onsite as needed for infrastructure and data center support
Employment Type: Full-Time
Department: Event Citadel / IT Operations

Event Citadel is seeking a Senior Infrastructure Systems Administrator to support and modernize a complex infrastructure environment that includes legacy Solaris systems, Linux and Windows servers, on‑prem hardware, SAN/storage platforms, networking/security components, web application infrastructure, and potential cloud modernization initiatives. This role is ideal for a senior Level 2 / Level 3 infrastructure professional who is comfortable supporting mission‑critical legacy systems while helping the organization prepare for future modernization.

The successful candidate will provide hands‑on infrastructure support, troubleshoot production issues, assist with storage and capacity planning, support server and network infrastructure, and help reduce dependency on a small number of senior technical resources.

• Support and maintain legacy Solaris 10 / Solaris 11 production environments.
• Administer and troubleshoot Linux and Windows server systems.
• Support on‑prem infrastructure, including servers, switches, SAN/storage devices, and related hardware.
• Assist with storage capacity planning, monitoring, troubleshooting, and future storage modernization.
• Support Linux and web server modernization initiatives.
• Provide Level 2 / Level 3 escalation support for infrastructure, network/security, and systems issues.
• Help maintain and improve monitoring, alerting, documentation, and operational procedures.
• Support networking and security infrastructure, including IP management, switches, VPN/firewall-related coordination, and secure access.
• Participate in future infrastructure planning, including potential hardware refresh, AWS/cloud migration, or hybrid infrastructure modernization.
• Support production availability for mission‑critical Event Citadel systems and client‑facing platforms.
• Participate in after‑hours maintenance, urgent production support, and on‑call escalation as needed.
• Serve as a trusted technical backup to the IT Ops leadership team when senior staff are traveling or supporting live events.
• Work independently with minimal supervision while communicating clearly with technical and non‑technical stakeholders.

• 7+ years of systems administration, infrastructure engineering, or similar experience.
• Strong experience with Unix/Linux systems administration.
• Experience supporting legacy Solaris environments, ideally Solaris 10 and/or Solaris 11.
• Experience with on‑prem server infrastructure.
• Experience with SAN/storage administration, capacity monitoring, or storage troubleshooting.
• Strong troubleshooting and root‑cause analysis skills.
• Working knowledge of networking fundamentals, including TCP/IP, DNS, VPNs, routing, switching, and firewalls.
• Experience supporting production systems in a mission‑critical environment.
• Ability to work independently and operate as a senior escalation resource.
• Comfortable supporting both legacy systems and modernization initiatives.
• Ability to work onsite as needed for hardware, data center, or infrastructure support.

• VMware administration experience.
• AWS or Azure exposure.
• Apache/Tomcat or web application infrastructure support.
• PostgreSQL or relational database infrastructure support.
• Scripting experience with Bash, Power Shell, Python, or similar.
• Monitoring tools such as Grafana, Prometheus, Nagios, Zabbix, Solar Winds, or similar.
• Experience with hardware refresh projects.
• Experience migrating legacy systems to Linux, cloud, or modern platforms.
• Experience supporting event technology, registration platforms, analytics dashboards, or high‑availability client‑facing systems.
• Experience working in environments with aging infrastructure, legacy systems, and modernization roadmaps.