1.2.1 Virtual Machines

What are virtual machines?

VMS are entire OS running inside another OS
A user running Windows 11 could run a VM of MacOS- allow them to navigate the GUI of MacOS and install software on it
Running a VM helps access software that is only designed to run on specific OS
VM management software includes a Hypervisor that monitors all activity happening inside the VM

Cross-platform and forwards compatibility

Not all software is designed to run on all OS
Apple commonly makes software that only runs on MacOS for performance reasons
A windows user could run a VM of MacOS and install the software they need
Most software needs to be updated to work on the latest versions of OS
A user running the latest release of Windows may need to run a VM of a previous release of Windows to use an application that hasn’t received a forwards- compatibility update

In software testing

VMs are a way to create isolated test environments, that leave the host operating system unaffected
Isolated environments allow a developer to: monitor the way their software affects system performance, test on a clean-slate system, while no other applications are running
VM management software can create VMs that act like they have older hardware
This allows developers to build software that can be run on older hardware so that more users can use the software
A developer can test against various OS, e.g. MacOS, Linux and Windows, for greater compatibility
This is achieved through compiling into intermediate code and running against different OS

Consequences

VMs share the system hardware as the host OS
Over-use of VMs can exhaust the host OS of the system of CPU, hard disk and memory
VM software such as VirtualBox can set maximum limits on system resources
A low- specification machine could be configured to allocate only 1GB of memory and 20% of the CPU
OS are commonly free to download, but require an activation payment to access all features

Explain why the programmers of anti-virus software may make use of virtual machines when developing the updates

Recall 2 benefits of using VM in developing software
Link these benefits to some considerations needed when developing anti-virus software

Explain why the programmers of anti-virus software may make us of virtual machines when developing the updates

VMs are essential in developing anti-virus software updates for several reasons. VMs create an isolated environment that is separate from the host OS. This enables developers to safely work with virus test code that could risk the integrity of their own OS. VMs can also be configured to emulate various types of hardware. This allows developers to understand how their anti-virus software will perform on different devices and under different conditions, ensuring a wider range of compatibility

Thick Client advantages

More robust and more reliable. This results in greater “up-time” and availability of services
The preferred solution when you want to run heavy duty/resource hungry software applications
Can operated without relying on a constant connection to a central server

Thick Client disadvantages

Often more expensive and higher specification client computers required
Every client needs its own software installed, this increases the effort and time on the part of the network administration team
Due to the non-centralised, distrusted nature this method is more prone to integrity issues

Thin Client advantages

• Software updates done once on the server

• Easier to setup and configure

• More secure

Thin Client disadvantages

• Reliant on central server

• Dependent on powerful server which will be expensive

• Higher demand on bandwidth