As a follow-up to his previous article about the (minimal) overhead from logging, Kevin Schroeder has this new post focusing on the common belief that writing to the file system is the slowest method.

I had a conversation the other day by a person I respect (I respect any PHP developer who knows how to use strace) about the cost of file IO. My assertion has been, and has been for a long time, that file IO is not the boogeyman that it is claimed to be. So I decided to test a cross between those two posts.

His test was to write one million log records to two different sources - the normal physical file system, a RAM drive - one run with a file handle that's left open and the other with a new handle each time. He shows how he made the RAM drive and the PHP he used for the test (running in a VM). He graphs out the results with some interesting results...but you'll have to read the post for that.