quota behaviour of reflink()
Posted May 6, 2009 12:47 UTC (Wed) by utoddl
In reply to: quota behaviour of reflink()
Parent article: The two sides of reflink()
Interesting points, but remember: quota can be impacted by unrelated actions by other processes owned by the same or other users at any time, so user space needs to respond to space-related issues regardless of what quotas existed "moments ago". In fact, quota can be affected when the user takes no actions at all; the admin can change quotas, file systems can be resized, etc., and a user who was not over quota may suddenly be so even with no changes to his files.
Space-reporting tools can report variations of (1) actual space used by extant allocated blocks (modulo sparse files), (2) space free, (3) space that would be used in the case where a naive copy were made to another file system -- all of which are valid and different numbers. The "simple" question of how much storage is used is in fact complicated, our desire for simple answers notwithstanding.
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