Cloud and Virtualization Basics
Cloud and Virtualization Basics covers how compute, storage, and networking are abstracted and shared. The exam tests hypervisor types, IaaS, PaaS, SaaS, regions and availability zones, cloud storage choices, and container fundamentals.
Virtualization models
- Type 1 hypervisors run on bare metal, such as KVM-based platforms, Xen, and ESXi; type 2 hypervisors run on a host OS, such as VirtualBox and VMware Workstation.
- VMs virtualize hardware and run a full guest kernel; containers share the host kernel and isolate processes with namespaces and cgroups.
- Snapshots capture a point-in-time state; they are not a substitute for independent backups.
Cloud concepts
- IaaS provides virtual machines, networks, and block storage; PaaS provides managed runtimes; SaaS provides finished applications.
- A region contains multiple availability zones; deploying across AZs improves resilience.
- Object storage suits static assets and backups; block storage suits databases and VM disks.
- Security groups are stateful instance-level firewalls; network ACLs are stateless subnet-level filters.
Worked example
A web application serves large images and runs a relational database. Put images in object storage behind a CDN and the database on block storage with automated snapshots. Reasoning: object storage scales cheaply for immutable files, while databases need low-latency block devices and consistent backup procedures.
Traps
- Assuming a snapshot is a full backup.
- Treating a security group as stateless or as a subnet ACL.
- Assuming containers provide the same isolation as VMs.
- Making a storage bucket public to 'fix' access.