DHA -EOSS Computer Systems Analyst; Windows​/RHEL SA OS

Quantum Sky is searching for an experienced, high-caliber Senior Computer Systems Analyst (Windows/RHEL SA OS) to support the Defense Health Agency (DHA) E-Commerce Operational Systems Support (EOSS) contract in Aurora, Colorado.

In this mission-critical role, you will serve as the lead Operating System (OS) and Infrastructure Administrator responsible for the health, availability, performance, and cybersecurity posture of all DHA E-Commerce System (ECS) operating systems. The DHA ECS hosting environment resides in the Medical Community of Interest (MedCOI) AWS Gov Cloud East and comprises an enterprise dual-OS architecture consisting of Red Hat Enterprise Linux (RHEL 7/8) and Microsoft Windows Server (2016/2019/2022).

You will manage and configure operating systems supporting all core DHA ECS applications—including Oracle Federal Financials (OFF R12), the Enterprise Data Warehouse (EDW), PRISM, Management Tracking and Reporting (MTR/PAT), and web/proxy server tiers. You will lead OS upgrades, author custom Amazon Machine Images (AMIs), execute DISA Security Technical Implementation Guides (STIGs), coordinate with DHA Data Center Operations (DCOPS), and administer user and system-level accounts via the Application Virtualization Hosting Environment (AVHE).

• Operating System Administration & Maintenance Serve as the Senior System Administrator maintaining full lifecycle responsibility for all RHEL and Windows Server operating system instances across Development, Test, Quality Assurance (Pre-Prod), and Production environments.
• Lead the deployment, configuration, and migration of operating systems across major technology baselines (e.g., upgrading Windows Server 2016/2018 to Windows Server 2022, and RHEL 7 to RHEL 8/9) ensuring uninterrupted application performance.
• Administer OS-level executive software, server utilities, server roles and features, Active Directory services, and Group Policy Objects (GPOs) to maintain system consistency and policy enforcement.
• Monitor system resource utilization, memory, processor capacity, storage, and I/O performance; conduct sizing and capacity planning in coordination with DHA DCOPS.
• Cloud Infrastructure & AWS AMI Management Utilize the AWS Management Console to manage and monitor virtual server instances within the MedCOI AWS Gov Cloud East environment.
• Build, maintain, and harden custom DHA ECS Amazon Machine Images (AMIs) and deployment templates for distribution to the DCOPS Onboarding Team for rapid server provisioning.
• Coordinate onboarding forms, Change Requests (CRQs), Support Tickets, and Application Service Interruptions (ASIs) through the DHA Global Service Center (GSC) ticketing system for infrastructure modifications.
• Ensure strict segregation of environments: ensure developer access is restricted to Development and Test, while maintaining the production-equivalent ATO posture of the QA/Pre-Prod and Production environments.
• Cybersecurity Hardening, STIG Implementation & Vulnerability Remediation Apply DISA Security Technical Implementation Guides (STIGs) and maintain STIG checklists across all Windows Server and RHEL operating systems.
• Continuously review and remediate vulnerabilities identified by the Assured Compliance Assessment Solution (ACAS) and Host Based Security System (HBSS) / Trellix scans, resolving operating system findings prior to production deployment.
• Deploy Information Assurance Vulnerability Alerts (IAVAs), security patches, hotfixes, and vendor service packs within mandated DoD timelines, eliminating the need for unapproved Plans of Action and Milestones (POA&Ms).
• Support the Information System Security Officer (ISSO) and Information System Security Manager (ISSM) in documenting RMF security controls, artifact…