Senior Systems Administrator/Engineer

Ramon E. Castellon

Los Angeles, CA ***** 323-***-**** ********@*****.***

CAREER PROFILE

Hands-on Senior IT Systems Administrator/Engineer with 15+ years’ experience in enterprise banking, financial services, global markets, business operations, applications specialist and end-user administration. I am actively seeking opportunities within the tech industry, particularly in data management, cloud, virtualization, DevOps, automation or an industry where I can leverage my experience in administrating, implementing and supporting complex IT infrastructure platforms. I am eager to contribute my skills and passion to a company that values innovation and data-driven decision- making.

CORE SKILLSETS

• Solution Provider • Technical Troubleshooter • IT Upgrades

• Interpersonal Skills • Systems Optimization • Azure, Intune, Endpoint

• Strong Communication • SDLC Specialist/Agile • Server OS Deployments

• Scalability • Business Continuity • Collaboration Efficiency PROFESSIONAL EXPERIENCE

Sr. Systems Administrator/Engineer

MUFG Bank Ltd 2018 – 2025

Administered and maintained physical and virtual server environments across Windows Server platforms.

Performed routine system patching, OS upgrades, and firmware updates to ensure security compliance and system stability.

Maintained accurate documentation for system configurations, maintenance procedures, and change management.

Optimized IT infrastructure supporting global markets operations, ensuring systems uptime for market-critical applications like Moody’s, Bloomberg, Misys, FIS, Fiserv, Saas, SAP and more.

SME for applications and systems utilized by global market teams like finance, treasure, market data, funding, trading floor, foreign exchange, risk and asset/liability management (ALM), QRM.

Systems manager for varies banking, finance, analytical platforms & SOX systems/compliance.

Assisted Azure Cloud migration, modernizing server infrastructure and improving operational efficiency.

Assisted dev team in deploying releases to production by leveraging Azure DevOps CI/CD pipelines.

Conducted troubleshooting and optimization of Azure resources to support developers.

Work close with Business Users during and after software releases to prevent production downtime.

Coordinated Windows AD migration to Azure Cloud Intune platform for users, devices, servers and applications.

Assisted with migration of on-premise infrastructure to Azure, resulting in cost savings.

Utilized monitoring tools such as SolarWinds, Splunk, and Azure Monitor to proactively track server health, availability, and performance.

Utilized Azure Application Insights to monitor and troubleshoot mission-critical applications, improving application performance and user experience

Provided real-time support to business users, production operations reducing downtime and ensuring uninterrupted computer activities.

Assisted and implemented automated disaster recovery solutions, reducing incident resolution and problem management.

Acted as key liaison between stakeholders, security teams, engineering, developers and vendors, driving technology improvements aligned with business needs.

Provided Tier 2&3 escalation support, participated in on-call rotations, and responded to critical incidents in 24x7 environments.

Managed IT security protocols, ensuring compliance with industry standards.

Implemented and maintained sophisticated computer platforms from physical to virtual solutions tailored to the unique demands of the operations environment, optimizing system performance and minimizing downtime for end-users.

Raised ServiceNow, Jira incidents, change records, or problems tickets for day to day operations.

Worked close with development teams when programming market data APIs (Bloomberg, Refinitiv, etc.) and teams when programming solutions for applications before software deployment.

IT Desktop and Server Engineer

MUFG Bank Ltd 2014 – 2018

Built and maintained standardized Windows system deployment images to ensure consistency, compliance, and streamlined desktop and server provisioning.

Deployed, configured, and supported Windows Server (2016/2019+) and Windows 10/11 environments, including hardware and software setup for enterprise computer systems.

Aligned endpoint deployments with existing technology stack to ensure seamless delivery and integration across business units.

Managed Microsoft Patch Management processes across desktops and servers using SCCM, WSUS, and Intune, ensuring patch compliance with organizational security standards.

Operated software distribution and endpoint management tools to maintain OS/application versioning and automate updates.

Developed and maintained documentation, support procedures, and SOPs to standardize desktop engineering workflows and processes.

Performed proactive system monitoring to optimize performance, improve reliability, and ensure endpoint security.

Delivered Tier 2 and Tier 3 support for end-user hardware, software, and Windows operating system issues across the enterprise.

Collaborated closely with business stakeholders, IT support teams, and vendors to resolve deployment and support issues effectively.

Demonstrated advanced troubleshooting skills for server, desktop, and application-related incidents in fast-paced environments.

Administered enterprise services such as Active Directory, Group Policy, DNS, and DHCP to support infrastructure stability.

Utilized enterprise-grade endpoint protection tools like CrowdStrike and participated in vulnerability and access control management.

Wrote and maintained accurate technical documentation and leveraged ticketing systems to track issue resolution.

Applied knowledge of networking fundamentals including VLANs, switch configurations, and system access policies to resolve connectivity and performance issues.

Contributed to team learning initiatives by adopting emerging technologies through Proof-of- Concept (POC) testing and internal workshops.

Lead Systems Administrator III/Data Center

Union Bank 2009 – 2012

Managed enterprise-grade Windows Server and Linux environments supporting core banking systems, trading platforms, and financial applications.

Administrated and supported technical and project team members to resolve system problems and application-specific issues.

Supported the stability, availability, and performance of enterprise systems (e.g., servers, systems, applications, network, databases, storage, security) by performing complex systems analysis to identify problems, trends, and opportunities for improvement.

Provided 1st and 2nd level support for enterprise systems and systems in one or more additional IT domains by diagnosing, troubleshooting, and resolving complex incidents to minimize system issues.

Managed to find solutions for unresolved or critical issues, risks, problems to system engineers.

Supported communications with product users and suppliers to share information, identify opportunities, resolve problems, prioritize customer requirements, and maintain continuous improvement through customer feedback.

Planed and performed complex system configuration, validation, monitoring and stress testing.

Assisted in installs, upgrades, or decommissions of designated systems, products, and infrastructure.

Created documentation of new and existing system configuration and procedural information, and ensures system configurations documentation is complete and accurate.

Planed the implementation of hardware and software changes into environments and one or more additional IT production environments by performing impact analyses of system changes.

Administrated and managed vendor support activities, as appropriate.

Participated in and influenced change management processes via SDLC process.

Maintained the modification, and documentation of complex and advanced applications.

Supported the development of guidelines to prevent and/or resolve recurring problems.

Recommended and executed performance tuning and optimization during UAT activities.

Participated in after-hours support rotations and incident response activities to uphold 24x7 availability of essential services.

Enterprise IT Field Service Engineer

Union Bank / 2006 – 2009

Installed and maintained complex network infrastructure, including servers, desktops, routers, switches, hubs, fiber optics, and other specialized LAN/WAN devices.

Supported desktop systems and peripherals at both hardware and software levels, including memory and disk upgrades, and I/O device configuration.

Moved and relocated IT equipment such as servers, computers, printers, routers, and switches at various worksites.

Performed bench-level hardware repairs on CPUs, printers, badge readers, and other endpoint devices.

Installed structured network cabling in walls, ceilings, and conduits; terminate patch panels, data plugs, and jacks.

Troubleshoot and resolved system issues through configuration changes, software installations, and hardware replacements.

Use ticketing/call tracking systems to log service requests, resolutions, and work performed; maintain asset inventory databases.

Created detailed as-built technical drawings and documentation for infrastructure deployments.

Provided user training and guidance on hardware and software usage; communicate technical instructions clearly.

Recommended improvements to hardware configurations and maintenance procedures.

Lead and mentor Digital Technicians, assigning tasks and providing technical oversight and training.

Ensured compliance with SOX and Security policies and contribute to an inclusive and equitable work environment.

Interfaced professionally with employees and external vendors; explain complex technical concepts clearly.

Worked independently with minimal supervision; travel to offsite locations in a timely manner.

On-call support for production problem resolution. Provided recommendations for system improvements, new applications and plans to improve service.

Pro-actively created and updated operational/system procedures, for hardware/software upgrade, planning and implementation.

Planned and organized the development of technical support protocol, maintain operating systems, respond to system users’ request, and evaluate software vulnerabilities. Tools & Technologies: SCCM, Intune, WSUS, CrowdStrike, Active Directory, DNS, DHCP, Windows 10/11, Windows Server 2016/2019+ Avaya, IPC Turret. Extensive experience with server hardware, including chassis, server motherboards, network cards, RAID controllers, and other add-ons. Monitoring & Optimization: Application Insights, SolarWinds, Splunk, ServiceNow, Jira Scripting & Automation: Familiarity with PowerShell & Python Professional Development: Continuous learning through VMware Hands-on Labs, Azure Training, DevOps workshops, Windows Server/Desktop, Apple Technology. Active participation in VMware, Microsoft, cloud computing forums, automation scripting and advanced technology. FORMAL EDUCATION / CERTIFICATION

CALIFORNIA STATE UNIVERSITY LOS ANGELES – 2006

Bachelor of Business Administration, Emphasis on Computer Information Systems CALIFORNIA STATE UNIVERSITY FULLERTON – 2009

Microsoft Certified Systems Engineer ID#6079784

REFERENCE UPON REQUEST

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