Marcus T. Holloway

Profile

Senior System Administrator with 9 years of experience managing hybrid on-premises and cloud infrastructure for mid-market and enterprise environments. Specializes in Windows Server, VMware virtualization, and Active Directory governance across multi-site organizations. Reduced unplanned downtime by 74% at current employer and cut licensing overhead by $210K annually through infrastructure consolidation.

Work Experience

Senior System AdministratorMar 2019 - Present

Lodestar Financial Group, Austin, TX

Architected and migrated 340-server VMware vSphere 7 environment to a hyper-converged Nutanix cluster, cutting hardware refresh costs by $210K annually and reducing VM provisioning time from 4 hours to 18 minutes.
Designed and enforced a tiered Active Directory OU structure with Group Policy hardening for 2,800 user accounts, reducing privilege-escalation incidents by 91% over 18 months as measured by SIEM alerting.
Built a PowerShell-driven patch management pipeline integrated with WSUS and ServiceNow, achieving 98.6% patch compliance across 1,200 endpoints within 72-hour SLA windows.

System AdministratorJun 2016 - Feb 2019

Veritas Health Systems, Dallas, TX

Administered a 220-node mixed Windows Server 2016/Linux (RHEL 7) environment supporting 14 clinical sites, maintaining 99.94% uptime against a 99.9% contractual SLA.
Deployed and tuned a Veeam Backup & Replication solution protecting 85 TB of patient data, reducing average recovery time objective from 6 hours to 47 minutes during DR tests.
Led Office 365 tenant migration for 1,600 mailboxes from on-prem Exchange 2013, completing the cutover 11 days ahead of schedule with zero data-loss incidents.

Junior System AdministratorAug 2014 - May 2016

Brightline Technology Partners, San Antonio, TX

Managed day-to-day operations of 80-seat Windows Server 2012 R2 and Hyper-V environment, resolving 94% of Tier 2 tickets within a 4-hour SLA.
Standardized server build process using Sysprep and MDT imaging, cutting new-workstation deployment time from 3 hours to 35 minutes per unit.
Documented 60+ runbooks and network diagrams in Confluence, reducing onboarding time for new IT staff by an estimated 40%.

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