slapd.conf questions

[Franky Van Liedekerke <liedekef@pandora.be>]

(repost on openldap-devel since I got no response on openldap-general)

Hi, I have some questions about slapd.conf parameters which are not very
clearly explained in the man pages:

1) concurrency
   what does it do? how does it affect performance?
2) dbsync
   the manpage gives the syntax
   dbsync <frequency> <maxdelays> <delayinterval>
   but the frequency is never explained. So can somebody give an example
   with the necessary explanation?
3) dbnolocking
   what are the risks? corrupted indices, search failures...? I don't
   understand "may improve performance at the expense of data security"
4) threads
   what's the impact of lowering/increasing it for ldap with
   lot's of reads and writes?

tx for any response Franky