BDB Cache Size

[ldap@mm.st]

One of the recommended ways we learned via this list (and other sources)
to determine the the bdb cache size is to get the size of the entire db
using this: "du -ch /var/lib/ldap/*.bdb".  Which we have done and seems
to be working good for the initial settings for our ldap rebuild.  We
have "set_cachesize 0 4153344 1" in our DB_CONFIG and the command
returns 4.1M.  We are going to put a simple monitor script in place to
keep an eye on the db size so we will have an indication that the cache
size may need to be increased as the size of the db grows.  

Does anyone have any recommendations for  a threshold to use for
increasing the cache setting?   In other other words, if the db size
grows 10% larger than the cache setting, is that a good time to let the
admins know it is time to raise the cachesize?  Just looking for
suggestions on something to use as a trigger in a script.