Virtual machine style refers to the design and architecture of virtual machines and hypervisors that emulate real or hypothetical computing devices. This includes the virtual hardware components, system resources, and operating systems of the simulated computer environment.
The virtual machine style can impact performance, security, compatibility and other factors in how well it runs software, executes processes and manages system workloads. Common virtual machine styles include system virtual machines, process virtual machines and application virtual machines.
System Virtual Machines
A system virtual machine provides a complete platform that behaves like a real computer with virtualized hardware. The virtualized components include a CPU, memory, storage, networking interface and more. A hypervisor manages these components, allowing multiple system VMs to run side-by-side:
- Common in cloud and virtualization platforms like VMware, Hyper-V, VirtualBox and Xen.
- Allows different guest operating systems like Windows, Linux or BSD to run on the same host machine.
- Provides strong isolation, good performance and hardware virtualization support.
Some downsides are lower compatibility for older operating systems and higher overhead from fully virtualizing system hardware.
Process Virtual Machines
A process VM executes a single application rather than a full operating system. It virtualizes the programming process at runtime to translate code and provide everything needed for that process:
- Used in Java Virtual Machines (JVMs), the .NET Framework CLR, and programming frameworks.
- Faster startup and generally has lower overhead than full system virtualization.
- But provides less isolation and is limited to applications running in that framework or language.
Process VMs focus on portability and security via abstraction from the host OS and hardware.
Application Virtual Machines
Application VMs are another type of process VM that encapsulate not just programming processes but also userland resources like shared libraries, configuration files and more. Everything needed to run an app self-contained:
- Achieves greater app portability across OS platforms.
- Better application security through isolation.
- Simplifies app installation and management.
Popular technologies here include containers and sandboxing tools, as well as mobile app framework SDKs.
So in summary, virtual machines present simulated hardware and software stacks that allow greater flexibility in how systems run. Design factors impact their security, performance, compatibility and ease of use.
Comparing Virtual Machine Styles
|Fully virtualized PC hardware and guest OS
|Strong isolation, hardware support
|Compile & process code in managed environment
|Portability, security, fast startup
|Limited app support
|Sandboxed container with app and libraries
|Fast, portable deployment
Optimizing Virtual Machine Performance
There are some techniques that can help optimize virtual machine performance:
Minimize CPU Overhead
- Avoid overprovisioning CPU resources which can lead to contention. Right size VM vCPU cores.
- Use newer/faster host CPUs with virtualization optimizations.
- Profile workloads to identify if RAM or CPU bottlenecks exist.
Use Paravirtualization Providers
Paravirtualization (PV) guest tools for disk, memory, networking & timekeeping reduce emulation overhead by using special drivers rather than virtual hardware for some tasks.
Don’t Overcommit Memory
Setting fixed memory allocations minimizes thrashing problems when host runs out of spare RAM.
Use Solid State Disks
SSDs provide faster read/write speeds, lower latency which improves VM app experience.
Adjust Network Options
Network throughput can be improved by separating VM/host traffic, using VLANs to isolate traffic types or bypassing virtual network adapters to talk directly to physical NICs.
Virtual Machine Security Best Practices
Some key ways to enhance security for VMs include:
- Isolate VMs using VLANs, firewall rules and host networking policies to avoid inter-VM attacks.
- Encrypt VM Disks using built-in encryption options or third party tools.
- Utilize Security Features like VM shielding/introspection, malware prevention modules, VPN gateways and more. Many hypervisors now include advanced security capabilities.
- Monitor Activity with logging inside the VM guest and on the host for suspicious events.
- Enable Backups & Snapshots to facilitate restoration after infection or compromise.
- Patch & Harden VM Hosts since exploits here can impact guest VMs. Keep hypervisor platforms updated.
- Standard Security Controls like endpoint protection, firewalls, trust controls and network segmentation help protect VMs as well.
Use Cases & Applications
There are many practical use cases and applications that leverage virtual machines:
Software Development & Testing
Quickly spin up VMs with specific configurations on the fly for building software or testing different environments.
Save on hardware costs by running multiple servers as VMs on high capacity hosts. Helps reduce data center footprint.
Replicate VMs offsite using backup tools for operational resiliency when outages happen.
Public cloud providers rely extensively on VMs to deliver computing resources to customers in a scalable manner.
Legacy Application Support
Older apps can run on modern hardware using a VM with a supported guest OS environment.
Isolate untrusted programs inside a container VM to limit damage from malware or compromise.
Centralize management of user desktops and apps by hosting them within VMs running on servers instead of local PCs. Enables remote access.
Virtual Machine Management
Most hypervisors include management consoles or standalone tools to administer VMs:
- Provision virtual machines by installing guest operating systems and allocating resources like vCPUs, RAM, and disk.
- Monitor resource usage for tracking performance, bottlenecks and capacity.
- Live migration moves running VMs between physical host servers without disruption. Useful for hardware maintenance.
- Storage management features like snapshotting, thin provisioning and Storage vMotion facilitate backup, business continuity and storage flexibility.
- Access controls manage user permissions around VM access, actions and resources.
- Orchestration tools help automate VM deployment, configuration, scaling and interoperation.
Robust tools are vital for efficiently operating virtual infrastructure at scale.
Transitioning to Virtual Machines
For organizations looking to adopt virtualization, focus initial PoCs and pilots on targeted apps then refine processes before expanding. Phase in business critical systems slowly after establishing proficiency. Other tips:
- Involve stakeholders early across infrastructure, security and app teams.
- Assess workloads for virtualization suitability. Prioritize easy wins first.
- Validate backup/recovery and continuity processes work.
- Budget for potential hypervisor licensing, hardware and training costs.
- Instrument VMs to establish performance baselines before go-live.
With careful planning and skills transfer, virtual machines can then safely deliver operational benefits.
Virtual machine style comes down to the type of virtualization used and what system layers are abstracted or simulated. The major categories include system VMs that fully emulate hardware, process VMs that compile app code through a managed run time and application VMs that provide self-contained app sandboxing.
There are performance considerations around minimizing overhead as well as best practices for securing virtual infrastructure. Use cases range from cloud computing to disaster recovery to legacy app support. With mature products and oversight, virtual machines unlock flexibility and efficiency.
- Virtual machine style impacts security, compatibility and performance factors.
- System VMs fully emulate computers while process VMs focus just on compiling code.
- Application VMs provide portable, self-contained app sandboxing.
- There are several techniques to optimize VM efficiency like sizing correctly and using paravirtualization.
- Security requires isolating VMs, encryption, activity monitoring and applying standard controls.
- Use cases include software development, server consolidation, cloud infrastructure and more.
- Management capabilities help provision, monitor, migrate and backup VMs at scale.
Frequently Asked Questions:
- What is the difference between a system VM and a process VM?
A system VM virtualizes an entire computer including CPU, memory, storage and more to run a complete operating system. A process VM instead executes application code and processes in a managed environment, not a full OS.
- What benefits does a virtual machine provide?
Benefits include hardware consolidation, improved disaster recovery, legacy app support, greater portability, the ability to sandbox untrusted code and more flexible provisioning.
- What are some tips for improving VM performance?
Enable paravirtualization drivers, properly size vCPU & RAM, use SSD storage, monitor for bottlenecks, optimize networking and minimize CPU resource over commitment.
- How can you make VMs more secure?
- Isolate VMs using VLANs and firewall policies, encrypt storage volumes, enable security modules in the hypervisor, capture detailed activity logs and keep VM hosts hardened and patched.
- What is virtual machine management used for?
It helps admins provision, monitor, migrate, backup and orchestrate VMs at scale across a multi-server environment while controlling access and resource usage.
- What apps are best suited to run on VMs?
Ideal apps have modest resource demands, require specific OS dependencies or libraries, are stateless and portable, and demonstrate good performance when virtualized during testing.
- What skills are needed to work with virtual machines?
System administration, virtualization software expertise, networking, storage configuration, performance monitoring/tuning and automation skills are all important for VM management.
- How do you migrate existing servers to a virtualized environment?
Take an incremental phased approach. Start by identifying candidate apps, testing their virtualization compatibility, establishing resource requirements and policies, validating backup & recovery workflows, and budgeting for licensing and infrastructure needs before transitioning.
- What are the anti-malware protections offered with virtual machines?
Leading hypervisors have built-in anti-malware tools that can shield VMs from infection. There are also specially designed endpoint security platforms optimized for virtual infrastructure.
- Can virtual machine snapshots help with disaster recovery?
Yes, VM snapshots capture the state of a VM which can be used for quick restoration in a disaster scenario. Snapshots can also help with testing or rolling back updates.
- How does desktop virtualization differ from server virtualization?
Desktop virtualization hosts end user desktop operating systems and apps centrally in the data center rather than on local PCs. This enables greater management, security and accessibility benefits.
- What is virtual machine high availability?
It provides automated failover and redundancy of VMs using clustered hypervisor hosts and replication so that services running inside VMs can continuously operate through outages.
- What are the licensing considerations with virtual machines?
Operating systems and apps running inside VMs typically still need licensing, along with the hypervisor software itself which often use a tiered model based on sockets, cores or VMs under management.
- Can virtual machines improve business continuity capabilities?
Yes, features like live migration, high availability, backup/recovery and snapshots can reduce downtime risks by keeping VMs running through host maintenance and failures.
- What programming frameworks use process virtual machines?
- How has virtualization enabled cloud computing models?
Cloud providers leverage large virtualized infrastructure to efficiently allocate shared computing resources on-demand to customers in a scalable, automated manner.
- What is a hypervisor?
The hypervisor manages pooled host hardware resources among virtual machines. Examples include VMware ESXi, Microsoft Hyper-V, KVM, Xen and Oracle VM VirtualBox.
- Are containers a type of virtual machine?
Containers rely on some OS-level virtualization features for app sandboxing but do not virtualize hardware like VMs, so they’re more lightweight and portable.
- Can legacy operating systems run on modern hardware using VMs?
Yes, outdated OSes can run inside VMs on newer hardware by virtualizing compatible legacy system environments and hardware that they support.
- Does virtual machine security replace the need for endpoints?
No, VMs still benefit from continued use of endpoint firewall, antivirus and host security controls across virtual infrastructure alongside isolation and encryption features.