I always called it a “bit-mass”. Like a thermal mass used in freezers in places where the power is not very stable.

I knew I didn’t invent the concept, as there’s so many systems that cannot recover if the disk is totally full. (a write may be required in many systems in order to execute an instruction to remove things gracefully).

The latest thing I found with this issue is Unreal Engines Horde build system, its so tightly coupled with caches, object files and database references: that a manual clean up is extremely difficult and likely to create an unstable system. But you can configure it to have fewer build artefacts kept around and then it will clear itself out gracefully. - but it needs to be able to write to the disk to do it.

Now that I think about it, I don’t do this for inodes, but you can run out of those too and end up in a weird “out of disk” situation despite having lots of usable capacity left.