Senior Platform Engineer specializing in Kubernetes, cloud infrastructure, and secure CI/CD pipelines. I build and support platforms that developers can be enthusiastic about.

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Recent Posts

Welcome to My Technical Blog

December 02, 2024

Welcome to my technical blog! I’m Xavier Lopez, a Senior Platform Engineer with over 10 years of experience in DevOps, cloud architecture, and platform development. Also, I’m just gonna come clean and tell you that my friends Claude and ChatGPT are heavily involved in this effort. We’re using this as an opportunity to get to know each other.

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Network Concepts

December 06, 2023

  • Layer 2 and 3 of the Open Systems Interconnection (OSI) Model. An explainer.
    • Data Link Layer (Layer 2):
      • Functionality: This layer is primarily concerned with the local delivery of frames between devices on the same network.
      • Devices: Switches operate at Layer 2.
      • Addressing: Devices on this layer are identified by MAC (Media Access Control) addresses.
      • Data Unit: The frame is the basic data unit at Layer 2.
    • Network Layer (Layer 3):
      • Functionality: This layer is responsible for logical addressing, routing, and forwarding of packets between devices on different networks.
      • Devices: Routers operate at Layer 3.
      • Addressing: Devices on this layer are identified by IP (Internet Protocol) addresses.
      • Data Unit: The packet is the basic data unit at Layer 3.
  • VLAN Explainer
    • VLANs (Virtual Local Area Network):
      • Purpose: VLANs are used to logically segment a physical network into multiple broadcast domains. This segmentation helps improve network performance, security, and management.
      • Functionality: Devices in the same VLAN can communicate with each other as if they are in the same physical network, even if they are not physically connected t the same switch.
      • Implementation: VLANs are often implemented in switches, and devices within the same VLAN share the same VLAN ID.
      • Isolation: VLANs provide isolation at Layer 2, meaning devices in different VLANs cannot communicate directly at the Data Link Layer.
    • Subnets:
      • Purpose: Subnets are used to divide an IP network into smaller, more manageable segments. Each subnet has its own range of IP addresses.
      • Functionality: Devices within the same subnet can communicate with each other directly without the need for routing. Routing is required for communication between devices in different subnets.
      • Implementation: Subnets are implemented at the Network Layer (Layer 3) and are associated with IP addresses.
      • Isolation: Subnets provide isolation at Layer 3. Devices in different subnets require a route to communicate.

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Virtualization - Server

December 06, 2023

  • The Fundamentals of Server Virtualization:
  • Benefits
    • Efficiency:
    • Scaling by creating new VMs from templates.
    • Scaling by cloning VMs
    • Adding more resources on demand.
    • Admininstering many VMs from a single console.
    • Preserving state of a VM by snapshotting.
    • Policy-driven management.
    • Agility:
      • Rapid deployment of new applications.
      • Rapid scaling of new applications.
      • Break down admininstrative silos in IT and reallocate time to business-impacting projects.
    • Availability:
      • Abstraction. What is virtualized in software becomes relatively independent of underlying hardware, and therefore, portable.
      • High availability for all. Availability that was once very difficult and expensive becomes standard. This high availability is takes the form of fast replacement of suddenly unavailable resources, among other ways.
      • Improved data protection and disaster recovery through offsite redundancy.
      • Reduced energy consumption through efficiency of resource use during runtime and powering down during hours where they are not needed.
      • Increased business agility. Faster scaling.
    • Time savings:
      • Admininstering servers.
      • Protecting data.
      • Deploying new applications.
      • Replacing aging harwire.
      • Enabling HA and Loadbalancing.
    • Money:
      • Fewer servers = lower associated infrastructure costs.
      • More efficient administration of IT. Reallocation of labor.
    • Job security:
      • Deploy new apps faster.
      • Make server refresh easy
      • Spend more time on business-impacting projects.
    • Performance optimization. Hot-add / hot-plug. Resouces can be scaled up as needed (in some cases, without downtime)
    • Load balancing. Built-in load balancing ensures all applications get the resources they need, when they need them.
    • Resource sharing. Physical resources are shared and consumption is optimized.
  • Server Virtualization Architecture
    • Hypervisor: the software that runs virtual machines.
    • The server virtualization layer resides between the physical server and the virtualized servers.
    • Type 1 Hypervisor
      • Loaded directly on the hardware. Replaces the OS.
        • Examples: Hyper-V, ESXi / VSphere, KVM
    • Type 2 Hypervisor
      • Loaded in an OS running on the hardware.
        • Examples: Workstation / Fusion, Oracle VBox, Parallels
      • Requires and extra layer and therefore extra resources.
    • Virtual Host: The physical hosts that are running the hypervisor.
    • VMs and Virtual Resources:
    • Storage Virtualization
      • Virtual disk: These are actually just files, that represent entire virtual hard drives that can be moved.
    • Centralized management.
    • Management APIs.

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