How It Works

One of the primary goals of VCL is to deliver a dedicated compute environment to a user for a limited time. This can range from a virtual machine running an office suite to a machine room blade running high end software (i.e. a CAD, GIS, statistical package or an Enterprise level application) to a cluster of interconnected physical (bare metal) compute nodes. For years both ITECS (technical support for the College of Engineering) and the Central IT department, now called Office of Information Technology, struggled to efficiently provide remote access to high end computers for researchers and students. Visit History of VCL for more information.

The graphic below shows that remote users connect to the VCL Scheduling Application (the web VCL portal) and request access to a desired application environment. The application environment consists of an operating system and a suite of applications. VCL currently supports multiple versions of Window and Linux.

vcl_conceptual_overview

The VCL Infrastructure

The VCL infrastructure consists of three tiers: a web server, a database server, and one or more management nodes.

Web Server – The VCL Portal

  • System: Linux, Apache, PHP
    • The php based web application is the heart of VCL and provides tools to request, manage and govern all VCL resources. All transactions occur with the database.

Database Server

  • System: Linux, MySQL
    • Holds all data related to VCL reservations, access controls, machine and environment inventory, log history, etc.

Management node(s) – The processing engine

  • System: Linux, vcld (perl), image library
    • There can be more than one management node.
    • The management nodes each control a subset of the VCL resources. These can be blades or virtual machines. Currently, a set of individual blades or virtual machines can only be managed by a single management node. Typically there are anywhere from 80-120 physical computer nodes (blades) under one management node. Again the physical computer nodes can either be running a bare metal environment or a Virtual Machine hypervisor.
    • Standalone machines can be controlled by more than one management node.
    • vcld – VCL middleware that processes reservations/jobs assigned by the VCL web portal. Based on the type of environment requested whether it’s bare metal image, or a virtual machine image, vcld ensures the image is loaded and makes it available for the requesting user.