Opening the odd spreadsheet
A supplier emails an analyst a data file with a strange name. She needs the numbers, but she does not trust the file. A technician opens it inside a pretend computer made of software. The file turns out to be bad. It wrecks the pretend computer. The real one is untouched.
That story shows several features of a virtual environment at once.
Key words
| Word | What it means |
|---|---|
| Isolation | keeping each virtual machine apart from the others |
| Sharing | many virtual machines using one real computer's parts |
| Aggregation | joining many real machines to act as one big pool |
| Emulation | making one kind of computer act like another |
| Portability | being able to move something to another place and run it |
| Managed execution | the hypervisor controls how each virtual machine runs |
| Snapshot | a saved copy of a virtual machine at one moment |
| Virtual machine | a computer made of software that runs inside a real one |
| Hypervisor | software that makes and runs virtual machines |
| CPU | the main processor of a computer |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can describe seven features of virtual environments and give an example of each.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Isolation, security and managed execution
Isolation: each VM is kept apart. A crash or a virus in one does not reach the others.
Increased security: because of isolation, you can test risky files in a VM, and a snapshot lets you roll back after damage. Managed execution: the hypervisor decides how much CPU and memory each VM gets, and can start, pause or stop it.
Sharing, aggregation and emulation
Sharing: many VMs use one real computer, and its CPU and memory are split between them.
Aggregation: the opposite. Many real computers join together as one large pool, so one big job, such as a huge analysis, can use them all.
Emulation: a VM can imitate another kind of computer or an old system, so old software still runs.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.