Windows Updates: storage, quota and rotation
Set the disk allowance, understand rotation of super-cache files and metric retention.
In Status, click Modify on the Local update cache card.
The same disk allowance covers the super-cache and the approved content objects of the decision-source mode.
Current usage, storage limit, keep downloaded files and metric retention.
Current usage
The bar compares the space in use with the limit in service.
It shows the stored files, the space reserved for downloads in progress and the space left for new files.
It appears only when the listener is running.
Set the storage limit
Enter the allowance in Local storage limit, in GiB.
Decimals are allowed, for example 0.5.
One GiB is 1,073,741,824 bytes.
The limit goes from 1 byte to 1,048,576 GiB.
Below the field, the form says how much of the new limit the files already use.
A limit below the space already used is accepted.
New files are then relayed until space is freed.
Keep downloaded files
When Keep downloaded files is on, each file a computer downloads is stored and served again to the other computers.
When it is off, files are only relayed.
The limit still applies to the files already stored.
What happens at the limit
| Situation | Behaviour |
|---|---|
| The requested file is in the cache | Serve the local file. |
| A missing file fits in the limit and the free space | Download, check and store the file. |
| A missing super-cache file does not fit | Remove the least requested super-cache files, then store the new one. |
| Rotation cannot free enough space | Relay the file without storing it. Nothing is removed. |
Artica also keeps at least 1 GiB free on the file system.
Rotation
Rotation applies to the files of the super-cache only.
Approved content objects of the decision-source mode are never removed.
- Artica first checks that removing every eligible super-cache file would free enough space.
If it would not, nothing is removed and the file is relayed. - Files with the fewest requests over the rotation window go first.
- When two files have the same count, the one requested longest ago goes first.
- A file that is being downloaded is never removed.
A request counts once per computer and per day.
The rotation window is set in the Microsoft super-cache settings.
The default is 30 days.
The Microsoft super-cache card shows the files removed by rotation and the files relayed without storage.
What counts as used space
The storage directory is /home/artica/windows-update.
Super-cache files live under flow/, approved content objects under objects/.
Used space also includes temporary transfers, quarantine files and download reservations.
The limit controls new files.
It does not cap the metric database.
Leave free space for databases and the operating system, and monitor the file system itself.
Metric retention
Set Metric retention in days from 1 to 3650 days.
The default is 90 days.
Retention removes old minute samples.
It does not remove cached files.
Lifetime counters remain after old samples expire and after a restart.