The survey that came back by lunch
A small team collects a town survey. By Friday the file holds 2000 answers. On Monday morning every file on the team drive is locked, and a note asks for money.
The analyst stays calm. Sunday night a copy went to a disk kept in a drawer, away from the computers. By lunch the survey is back.
A good copy turns a disaster into a slow morning. Today you learn the kinds of copy and the habits that keep data safe.
Key words
| Word | What it means |
|---|---|
| Backup | A copy of data kept safe in case the first is lost. |
| Full backup | A copy of all the data. |
| Incremental backup | A copy of only what changed since the last backup of any kind. |
| Differential backup | A copy of everything that changed since the last full backup. |
| Restore | Putting backed-up data back. |
| Off-site | Stored in a different place from the original. |
| Update | A new version of software that fixes weaknesses or adds features. |
| Firmware | Software stored inside a device, such as a router. |
| Driver | Software that lets the computer talk to a device such as a printer. |
| Air gap | A computer or network with no connection at all to other networks. |
| Network | Computers joined together so they can share data. |
| Malware | Harmful software. |
| Router | A device that passes traffic between networks. |
| Ransomware | Malware that locks files and demands money. |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can describe three kinds of backup and say how updates and air gaps lower risk.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Three kinds of backup
Full backup. Everything, every time. Slow and big, but one copy is all you need to restore.
Incremental backup. Only what changed since the last backup of any kind. Quick and small, but to restore you need the full copy plus every incremental after it.
Differential backup. Everything changed since the last full backup. Bigger each day, but you need only two copies to restore.
Worked example: records in each backup
| Day | Full (2000 records) | Incremental | Differential |
|---|---|---|---|
| Sunday: full backup | 2000 | 2000 | 2000 |
| Monday: 20 new answers | 2000 | 20 | 20 |
| Tuesday: 20 more | 2000 | 20 | 40 |
| Wednesday: 20 more | 2000 | 20 | 60 |
| Restore on Wednesday needs | 1 copy | Sunday, Monday, Tuesday and Wednesday: 4 copies | Sunday and Wednesday: 2 copies |
The cells students fill in are left blank in this preview.
Check: which backup is it?
Have a go
Check: which backup is it?
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.