Thanks again to Patrick and others for scripting these things.
With automation in mind: would it be feasible to add options, for the user to specify any one or more of the following?
- a percentage to be made free – at the pool level – before reception
- an amount, in MB, to be made free – at the pool level – before reception
- a percentage to be made free – at the file system level – before reception
- an amount, in MB, to be made free – at the file system level – before reception
- a percentage to be made free – at the pool level – after reception
- an amount, in MB, to be made free – at the pool level – after reception
- a percentage to be made free – at the file system level – after reception
- an amount, in MB, to be made free – at the file system level – after reception
BackgroundThe following screenshot (from a small
collection of files on Wuala) demonstrates what can happen if the user is, like me, careless about free space at the receiving file system.

Also: I don't have links handy, but I'm aware of recent/ongoing work by developers of ZFS to more effectively estimate – before send begins – the amount that's to be sent.