My team is working on a (phone) app which continually logs data to the internal storage or SD card. This data is periodically sent to a server. (No worries - this is not spyware, and the users are aware of what's happening.)
Since we're logging to storage, it might happen that the storage is full, so we can no longer write data. Even if we delete old log files, the storage may fill up through other applications.
In theory, we could just stop logging, and allow other functionality to keep working. But it seems better to inform the user about this situation, so they can take action (remove apps or media to free up space).
If we inform the user, what can we show, such that the user actually knows what to do?
Edit: in response to comment:
How critical is logging to the main functionality of the app?
It's a crowdsource app. Therefore, not sending data will allow the app to function to the user, but it will not contribute anymore to the crowd.
Which mobile platform(s) will the app use?
Using Xamarin, we're developing for Android, iOS and Windows Phone.
Is keeping all the old log files necessary to the functionality of the app?
It is highly preferable, but not strictly necessary.
What level of technical knowledge / skill do you anticipate from an average random user?
Just like the average phone user, with the exception that it is an app for in a car. So the user at least has a driving license.
Why are you opting to keep local logs vs. a cloud backup?
Everything is sent to the cloud, and then deleted from the phone. This question is applicable in case the internet connection is interrupted.