On Wed, Feb 02, 2011 at 02:44:27PM -0800, Chaim Rieger wrote:

is there a guideline for the maxdirsize setting based on the hardware ?

The default (in 6.5 and later) is 1% of system memory, so it is somewhat based on the hardware already.

RAM is the main resource because the directory contents might get read and cached. That would push out a lot of stuff if it's too large compared to the size of RAM.