It's the same as old VW beetles which had a reserve gas tank. When you ran out of gas you opened a valve and you could limp to a gas station. Less likely to fail versus a 1950's era gauge that is telling you you're low. Also impossible to ignore it.
In scuba diving there used to be "J-valves". When you had 50 bar left in the tank they would cut out. Then you would pull to reenable your air and return to the surface. Unsurprisingly they are no longer popular.
It's not that straightforward IMO. Would this file be deleted before the space is filled? If so, there is alerting in place, and it assumes there's a way to delete files before space fills up. If this file is deleted after space fills up, how is this different from not having the file, other than making finding files to delete easier? Then what happens after that? If you delete the file and realize there's nothing else to delete, you'd have to solve the problem the same way if you didn't use this method.
What if the solution required some amount of free space? (eg. installing a package or swap)
Don't think I've ever encountered a critical issue where "add more swap" would be a serious disaster recovery solution. I've certainly seen situations where swap was nearing 100% full, and although I would have minutes off wall-clock time to formulate a strategy, those minutes have never allowed me to input more than a handful of characters or so.
Perhaps consolidate/defrag once a year. Even monitoring total usage more often than that is probably not worth the effort - just buy ample cheap storage.
Also, there was a tradition to split drives into OS, DB, DB Logs. That was mostly a rust performance thing and these days is probably just voluntary management overhead.
RAM is another story.
> "just buy ample cheap storage"; "That was mostly a rust performance thing and these days is probably just"
In the UK a 6TB enterprise rust disk is £150 and a 2TB enterprise SSD is £300, it's 6x the price to SSD everything, and take 3x more drive bays so add more for that. And you can never "just" buy more storage than you ever need - apart from the obvious "when you bought it, you thought you were buying enough, because if you thought you needed more you would have bought more", so that amounts to saying "just know the future better", but it can't happen because Parkinson's Law ("work expands so as to fill the time available for its completion") applies to storage, the more there is available, the more things appear to fill it up.
Room for a test restore of the backups in that space. Room for a clone of the database to do some testing. Room for a trial of a new product. Room for a copy of all the installers and packagers for convenience. Room for a massive central logging server there. What do you mean it's full?
And if you haven't overprovisioned their max space, you may as well not be using dynamic allocation and use fixed size disks.
Even then, snapshots will grow forever and fill the space, and then you hope you have a "spacer.img" file you can delete from the datastore, because you can't remove snapshots when the disk is full and you're stuck. It's the same problem, at a lower level.
Yes, I've seen that time bomb go off on multiple occasions. Never on my watch though.
> This is 2021 and the technology is from the 90s I don't see how this is a valid point. Is integrated circuit technology outdated because it was developed in the 60s?