Instant domain-error.log

[kilburn]

The current logfile approach is inherently flawed, as apache uses WAY too much open files to do this job, which is known to cause trouble when your number of hosted domains grows high.

Mysql would solve this and would make it easier to deploy setups involving multiple machines (this is the envisioned upgrade path for ispcp), but as you quickly noted, it is an overkill for single-system setups.

There was a lot of discussion about this in the past (you should find the thread if you search hard enough).