What

We have a cron job in Pure named "Preserved Content Maintenance". 
What does it do, and why do we have it?

Why

This job was introduced in Pure 5.11, and replaces the old jobs "'Local file store health" and "'Cleanup temporary files"

The job clean up files in the storages that are no longer in use by Pure (mostly temp files) and validates that the .status files have not been corrupted, and restores them if they have.

Temporary files in Pure that needs to be removed are often left over from a job, or cases where someone started to add new content to Pure, and uploaded a file, but then regretted and never saved the metadata. 

One thing worth noting is, that if the job log has warnings like this:

And you think there could be a good reason why there should be files to delete, then you need to increase the value "Maximum number of files to clean up in" in the job configuration, because even though you might think that we will delete 250 and try again with the rest at the next run, in reality the number in the configuration is not how many the job will delete on a run. 
Its a limit saying, we will not remove anything, if there is more than x files.

The limit is meant as a safety switch to prevent the job from deleting large number of files if the storage mount points are badly configured.

From Pure version 5.18.0 there is no limit on temp stores, only permanent stores, this is because the default limit has turned out to be a bit restrictive for the 'temp' store.

In general, if you see any warnings or errors from this job, and you have not made changes in Pure that should result in large deletions of files in a file store, then please contact Pure support, so we can help verify if there is a error with the configuration, or if its safe to continue.

More information

How Does Uploads to Pure Work 
Pure Academy: Keeping your Pure healthy