Ah I see where you are coming from. You see the spacer as a way to prevent a problem that should be prevented by better monitoring. But that's not what it is for. It's for quickly providing a stopgap so that you have time to solve the root cause without enduring more downtime.

If you've had a disk go full on you, what's the first thing you do? For me, I log in and start looking for a log file to truncate to buy me a few megs of space, at least. This spacer file is just a guaranteed way to find the space you need without having to hunt for it.

Also it doesn't HAVE to be 8GB. On most systems I think a 500mb file would be every bit as effective.