Of late, we've had a rash of customer run out of disk space, and then have to perform resyncs or other actions to make their instance consistent again after freeing up some empty space.

What if we made an option to pre-allocate a 2-3G "crash pad" file, which when we experience an out of disk scenario, we can steer records of the writes we'd like to have done into that file, and then crash, with an intention of being able to restart later on, and replay the missed writes, returning us to a consistent state.

This is very similar to regular journalling, but the key difference would be that the space is pre-allocated, so would be able to work around running out of space.

I've left out ~1000 implementation details I haven't worked out, mainly just noting the general thought.