Scaling bottom-up - best practices?

[Jan Lühr <openldap-list@stephan.homeunix.net>]

Hello,

for some time now, we're using openldap 2.4.11 on debian lenny and everything 
is fine - but: We've to scale.
Up to now our root-dn is dc=abc - our new root-dn ought to be: dc=xyz, having 
a subtree dc=abc,dc=xyz
The root-dn is set in some application's configs as base dn, furthermore, it's 
referenced in ldap-entries (dynamic overlay-groups).

Basically I can think of two strategies.
a) Change the root-dn within the directory and in all applications depending 
on it (con: error prone - pro: clean result)
b) Install a new server, proxy all requests to the old instance, removing 
dc=xyz on queries, add dc=xyz on responses. (con: complexity, pro: no changes 
in apps / Information depending on dc=abc)

Have you had similar problems? What did you do to solve 'em? What strategy do 
you recommend?

Thanks,
Keep smiling
yanosz