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

Position Summary
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.

Key Responsibilities

• 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.

Required Qualifications

• 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.

Preferred Qualifications

• VMware administration experience.
• AWS or Azure exposure.
• Apache/Tomcat or web application infrastructure support.
• PostgreSQL or relational database infrastructure support.
• Scripting experience with Bash, PowerShell, Python, or similar.
• Monitoring tools such as Grafana, Prometheus, Nagios, Zabbix, SolarWinds, 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.