This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I searched around a little and I see that this setting is deprecated. I don't know what version of Struts marked this as deprecated or what effect it currently has. My project has it set to 2, which I am sure is because that is what it was set at in a previous project.
Here is the documentation that I found:
The debugging detail level that controls how much information is logged for this servlet. Accepts values 0 (off) and from 1 (least serious) through 6 (most serious). DEPRECATED - Configure the logging detail level in your underlying logging implementation.