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Infrastructure · Virtualization

Virtualization

Abstracting physical hardware so multiple isolated virtual machines share one host, with live migration, snapshots and dynamic resource allocation.

IntermediateUpdated 2026-09-01

Overview

A hypervisor presents virtual CPU, memory, storage and network to guest operating systems. Consolidation improved hardware utilisation dramatically, but the more important operational gains were live migration, rapid provisioning and hardware independence.

Virtualization management platforms are Tier 0 assets. Whoever controls the hypervisor controls every guest on it, including domain controllers, backup servers and security tooling.

How it works

  1. 01Clusters pool hosts and provide automated restart of guests after host failure, plus live migration for maintenance without downtime.
  2. 02Shared or hyperconverged storage presents datastores; thin provisioning and deduplication reduce consumption at the cost of careful capacity monitoring.
  3. 03Virtual switches and distributed switches connect guests to physical networks, carrying VLAN tags from the fabric.
  4. 04Snapshots capture point in time state for short term rollback; they are not backups and degrade performance if retained.

Security considerations

  • Isolate management interfaces and vCenter/SCVMM equivalents on a dedicated management network reachable only from privileged workstations.
  • Require MFA and separate administrative identities for hypervisor management; do not reuse domain admin.
  • Patch hypervisors promptly, internet reachable management interfaces have been exploited at scale by ransomware groups.
  • Encrypt or at least tightly control access to datastores; a copied VM disk is a copy of everything inside it.

Common misconfigurations

  • Management interfaces reachable from user VLANs or the internet.
  • Domain controllers and their backups on the same host or datastore.
  • Snapshots left for months, filling datastores and risking consolidation failures.
  • Resource overcommitment without monitoring, producing unexplained performance complaints.