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Virtual Infrastructure Manager (VIM) Architecture & VM Lifecycle

Study material and explanations for Unit 3

Virtual Machine Life Cycle and Cloud Infrastructure Management

Managing thousands of virtual machines across a cloud data center requires automated tools and well-defined operational stages.

1. The Virtual Machine (VM) Life Cycle

A Virtual Machine goes through five distinct phases from creation to deletion:

[ Provisioning / Create ] ➔ [ Running / Active ] ➔ [ Paused / Suspended ] ➔ [ Stopped / Off ] ➔ [ Terminated / Destroyed ]
  1. Provisioning (Creation): Allocating CPU cores, RAM, and disk storage from the cloud pool and installing the guest OS from an image template.
  2. Running (Active): The VM is powered on and executing user applications and processing network traffic.
  3. Paused / Suspended: RAM state is saved to disk temporarily so execution pauses without losing open programs.
  4. Stopped (Powered Off): The VM is shut down. CPU and RAM are returned to the pool, but the virtual hard disk remains saved.
  5. Decommissioned (Terminated): The VM is permanently deleted and its disk space is wiped clean.

2. What is Live VM Migration? (e.g., VMware vMotion)

Live Migration is the process of moving an entire running virtual machine from one physical host server to another physical server without interrupting the operating system or disconnecting users!

Why is Live Migration Needed?

  • Server Maintenance: An administrator needs to replace a faulty RAM stick on Server A. Instead of shutting down 20 client websites, the system moves the 20 running VMs to Server B in seconds with zero downtime.
  • Load Balancing: If Server A gets too hot or CPU reaches 95%, some VMs are automatically migrated to cooler, idle servers.

How Does Live Migration Work? (Pre-Copy Memory Mechanism)

  1. Copy Storage & Config: Both physical servers access a shared SAN storage pool.
  2. Iterative Memory Pre-Copy: Memory pages of the running VM are copied over the high-speed network to the destination server while the VM continues running.
  3. Final Switchover: The VM is paused on the source server for only a few milliseconds (unnoticeable to users), the remaining memory pages transfer, and execution resumes on the new host!

3. VM Snapshots

A Snapshot is a frozen point-in-time copy of a virtual machine’s disk and memory state.

  • Why Students & Admins Use Snapshots: Before installing risky software updates or modifying system files, you take a snapshot. If something breaks or Windows crashes, you can revert to the snapshot in 10 seconds!

💡 DAVV Exam Tip

Question (5 Marks): “Explain Live VM Migration and its significance in cloud data centers.”

  • Define Live Migration: Moving an active running VM between physical hardware without downtime.
  • Mention zero downtime and continuous business availability.
  • Give the hardware maintenance and load balancing use cases.