Linux Admin

Job Description: L3 Linux Administrator

Location: Irving, TX (Onsite 3 Days/Week)
Employment: Fulltime

Experience: 8–12 Years

Overview

We are seeking a highly skilled L3 Linux Administrator to support and enhance large-scale enterprise Linux environments. This role requires deep systems expertise, strong experience with Veritas Clustering (VCS), SAN/NAS storage, and hands-on collaboration with data center teams. The ideal candidate is a proactive problem-solver who can independently drive incident resolution, ensure platform stability, and improve BAU operations through automation and best practices.

Key Responsibilities

Linux Administration (L3)

• Administer and troubleshoot RHEL, Oracle Linux, CentOS, and SUSE in production environments.
• Diagnose complex OS issues: kernel panics, boot/GRUB failures, filesystem corruption, resource contention, SELinux/AppArmor denials.
• Perform OS patching and upgrades at scale; manage package repositories and kernel updates with rollback strategies.
• Implement and audit security hardening (firewalld/iptables, CIS benchmarks, PAM, SSH, sudo, auditd).
• Manage system services (systemd), cron/timers, user/group administration, sudoers, and system-wide configurations.

Veritas Cluster Server (VCS / InfoScale)

• Install, configure, and administer VCS for HA/DR across multi-node clusters.
• Build and maintain service groups, resource dependencies, LLT/GAB, I/O fencing, and quorum mechanisms.
• Integrate VxVM/VxFS for disk groups, volumes, filesystems, and application failover.
• Conduct DR drills, cluster failover tests, and analyze cluster-related incidents.

Storage Administration: SAN & NAS

• Collaborate with storage teams for LUN provisioning, zoning, and masking; validate multipathing (DM Multipath / PowerPath).
• Build and maintain filesystems (ext4/xfs/VxFS), fstab configurations, and autofs.
• Administer NFS/CIFS/SMB mounts, permissions, quotas, and troubleshoot locking issues.
• Diagnose latency, path failures, and I/O bottlenecks using OS-level and HBA/array telemetry.

Data Center & Hardware Coordination

• Work with data center teams for racking/stacking, cabling, console access, and onsite hardware triage.
• Troubleshoot hardware faults: CPU, memory, NIC/HBA, disks/RAID/SSD, backplane, PSU, fans.
• Manage OEM support tickets (Dell/HP/IBM/Cisco), RMAs, and post-replacement validation.

BAU Operations & Incident Management

• Act as L3 escalation for P1/P2 incidents; lead technical recovery and bridge calls.
• Perform comprehensive log analysis: journald, syslog, dmesg, audit logs, application logs.
• Develop and maintain SOPs/runbooks and knowledge base articles; drive RCA and corrective actions.
• Participate in on-call rotation and scheduled maintenance windows (change management, CAB, MOPs).

Networking (Host-Level)

• Troubleshoot TCP/IP, routing, bonding/teaming, MTU issues, host firewalls, DNS/DHCP, NTP/Chrony.
• Coordinate with network teams on L2/L3 connectivity, load balancers, and firewall rule updates.

Required Skills & Experience

• 8–12+ years of enterprise Linux administration with proven L3-level ownership.
• Strong hands-on expertise with Veritas Cluster Server (VCS), VxVM, VxFS, and HA/DR architectures.
• Solid SAN/NAS experience: LUNs, zoning, multipathing, NFS/SMB.
• Advanced troubleshooting skills in OS, storage, performance, and clustering.
• Scripting skills in Bash (Python preferred) and familiarity with Ansible.
• Knowledge of VMware/KVM and basic cloud concepts (AWS/Azure).
• Strong documentation habits for SOPs, MOPs, RCAs, and ITIL-aligned processes.
• Ability to work independently, lead incidents, and collaborate with cross-functional teams including DC, network, and storage units.