Construction
Measuring every day that nobody looks at
Your installation generates data continuously and most of it nobody reads. The day it is requested, it is worth exactly what was retained.
An operating installation produces records continuously: flows, levels, readings, operating logs, incidents. **The vast majority are never read by anyone**, and that is precisely why they are managed badly: it is hard to look after something nobody uses. Until a specific request arrives about a specific day, and then the whole value of the system concentrates on whether that day was kept or not.
The life cycle of a record nobody reads
| Moment | Who uses it | What usually happens to it |
|---|---|---|
| The day it is generated | The operator | A quick glance |
| The following week | Nobody | Filed, or not |
| The following year | Nobody | Lost in a system change |
| **The day it is requested** | **Everyone** | **It gets hunted for** |
Important
**A record nobody ever uses still has a perfectly calculable value: that of the day it is requested.** It is the whole argument in this position, and it needs stating explicitly because intuition says the opposite. The cost of keeping is small, constant and visible; the cost of not having is enormous, occasional and invisible until it happens. Systems designed looking only at the first always end up in the second.
What to decide once
- 1
What is kept and for how long
Decided, not inherited from the previous system by inertia.
- 2
Where it lives, and not on a local machine
System changes are where histories disappear.
- 3
What happens to anomalies
An odd reading with no explanation beside it is worse than no reading.
- 4
And who can consult it without asking permission
If someone has to be phoned, in practice it does not exist.
Watch out
The moment these archives are lost is not a deletion: **it is a migration**. The control system changes, the supplier changes, the server changes, and the previous history «stays there for now» — until that machine is retired. Nobody decides to lose it and nobody notices it is gone, because by then nobody was consulting it. Any system change should explicitly cover what happens to the old data, and almost none do.
Worth knowing
What operating records are mandatory for your installation, at what frequency, for how long they must be retained and who may require them **is determined by the applicable rules and your authorisation, and settled by your adviser or the competent body**. Here we cover the organisational part: how to retain and find records nobody consults until the day they are needed.
›Is keeping what nobody reads worth it?
It is worth exactly what not having it will cost the day it is asked for.
›What do I do with an anomalous reading?
Keep it with its explanation beside it. Deleting is the worst option.
›And when changing systems?
Decide explicitly what happens to the history. That is when it is lost.
A real case
The situation
Readings from a specific day two years ago are requested.
What you do
- Keeps records dated and accessible
What you get
It is answered by searching rather than reconstructing.
The situation
A system change leaves the history on a retired machine.
What you do
- Stores records off local machines
What you get
The migration does not take the previous years with it.
The situation
An anomalous reading appears with no explanation.
What you do
- Allows noting the context alongside the record
What you get
The anomaly is explained rather than raising suspicion.
The situation
Consulting the history means phoning whoever manages it.
What you do
- Keeps the archive available to whoever needs it
What you get
The query does not depend on one person.
The situation
Nobody knows what must be kept or for how long.
What you do
- Applies a uniform retention policy
What you get
The decision is taken once and applies itself.
The situation
Operating logs stay on paper at the installation.
What you do
- Captures the log on site and stores it at once
What you get
The record stops living in a physical folder.
This article answers
- how long to keep operating records
- continuous measurement data and its evidence
- asked for readings from two years ago
- what to do with the records the installation generates