I often read that it is best to increase this variable slowly. Can someone explain why? My status indicates that I should increase it... What is best practice / "slowly"?
In MySQL 5.6, this setting is treated a little different.
Here is an additional reference from MySQL Performance Blog about setting innodb_open_files.
Raising innodb_open_files to a big number should not be that all that troublesome, but please be sensible about the number you choose.