The drive in the skip
A school replaces old computers. The old hard drives go in a skip. Weeks later a stranger buys one and finds pupil records on it.
Deleting a file does not remove it. The last stage of the life cycle is as important as the first.
Key words
| Word | What it means | Example |
|---|---|---|
| Dataset | A collection of related data kept together. | Last year's register |
| Personal data | Data that can identify a living person. | A pupil name |
| Retention | Keeping data, often archived, for later use or because a rule says so. | Keep records for six years |
| Archive | To store data you rarely use in a safe place for the long term. | Last year's register |
| Destruction | Destroying data so it can never be got back. | Wiping a drive |
| Disposal | Getting rid of data and the storage it was on, in a safe and proper way. | A certified drive shredder |
| Retention policy | A rule that sets how long each kind of data is kept. | Rota: one year |
| Storage | The device or service that holds data. | A hard drive |
| Overwrite | To write new data over old data so the old data cannot be read. | Wipe with random data |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can explain retention and destruction, and put every stage of the data life cycle in order.
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.
Stage three: post-operations
| Part | What it means | Example |
|---|---|---|
| Retention | Archive the dataset for future use | Store last year's register safely |
| Destruction or disposal | Destroy the data and its storage safely | Wipe, then shred a drive |
The cells students fill in are left blank in this preview.
Why deleting is not enough
When you delete a file, the computer often only forgets where it was. The data stays until something writes over it.
Safe disposal overwrites the data, or destroys the drive. Keep a note of what was destroyed, when and by whom. Personal data must not be kept longer than needed.
Try it: what is past its keep date?
select dataset, keep_until
from holdings
where keep_until < '2026-03-01'
order by keep_until;
-- Try it: change the date to 2031-12-31 and press Run.